Template:Cite book/doc

Citation Style 1 templates

{{Cite arXiv}}	arXiv preprints
{{Cite AV media}}	audio and visual
{{Cite AV media notes}}	audio and visual liner notes
{{Cite bioRxiv}}	bioRxiv preprints
{{Cite book}}	books
{{Cite conference}}	conference papers
{{Cite encyclopedia}}	edited collections
{{Cite episode}}	radio or television episodes
{{Cite interview}}	interviews
{{Cite journal}}	academic journals and papers
{{Cite magazine}}	magazines, periodicals
{{Cite mailing list}}	public mailing lists
{{Cite map}}	maps
{{Cite news}}	news articles
{{Cite newsgroup}}	online newsgroups
{{Cite podcast}}	podcasts
{{Cite press release}}	press releases
{{Cite report}}	reports
{{Cite serial}}	audio or video serials
{{Cite sign}}	signs, plaques
{{Cite speech}}	speeches
{{Cite techreport}}	technical reports
{{Cite thesis}}	theses
{{Cite web}}	web sources not covered by the above
See also:
Meta-templates Specific-source templates Wrapper templates

This Citation Style 1 template is used to create citations for books. When citing an article in a periodical, use {{cite journal}}. For conference papers, use {{cite conference}}. For edited collections, use {{cite encyclopedia}}. For theses, use {{cite thesis}}.

Usage

Copy a blank version to use. All parameter names must be in lowercase. Use the "|" (pipe) character between each parameter. Delete unused parameters to avoid clutter in the edit window. Some samples may include the current date. If the date is not current, then the page.

Most commonly used parameters in horizontal format

To cite a book with a credited author {{cite book |last= |first= |date= |title= |url= |location= |publisher= |page= |isbn= |author-link=}} To cite a book with no credited author {{cite book |author=<!--Staff writer(s); no by-line.--> |title= |url= |location= |publisher= |page= |date= |isbn=}} To cite an online book that has been archived {{cite book |last= |first= |date= |title= |url= |dead-url= |location= |publisher= |isbn= |archive-url= |archive-date=}} To cite a book written in a foreign language {{cite book |last= |first= |date= |title= |trans-title= |url= |language= |location= |publisher= |isbn=}} To cite and quote an archived, two-author, foreign language book re-published as a PDF on an information aggregation service requiring a subscription {{cite book |last1= |first1= |last2= |first2= |date= |title= |trans-title= |url= |dead-url= |format= |language= |location= |publisher= |isbn= |archive-url= |archive-date= |via= |subscription= |quote=}}

Most commonly used parameters in vertical format

{{cite book |last= |first= |date= |title= |url= |location= |publisher= |page= <!-- or pages= --> |isbn= |author-link= }}

Full parameter set in horizontal format

{{cite book |last1= |first1= |author-link1= |last2= |first2= |author-link2= |last3= |first3= |author-link3= |last4= |first4= |author-link4= |last5= |first5= |author-link5= |display-authors= |author-mask= |last-author-amp= |translator-last1= |translator-first1= |translator-link1= |translator-mask1= |date= |year= |orig-year= |chapter= |script-chapter= |trans-chapter= |chapter-url= |chapter-format= |editor1-last= |editor1-first= |editor1-link= |editor2-last= |editor2-first= |editor2-link= |editor3-last= |editor3-first= |editor3-link= |editor4-last= |editor4-first= |editor4-link= |editor5-last= |editor5-first= |editor5-link= |display-editors= |title= |script-title= |trans-title= |url= |dead-url= |format= |type= |series= |language= |volume= |issue= |others= |edition= |location= |publisher= |publication-date= |page= |pages= |at= |nopp= |arxiv= |asin= |bibcode= |doi= |doi-broken-date= |isbn= |issn= |jfm= |jstor= |lccn= |mr= |oclc= |ol= |osti= |pmc= |pmid= |rfc= |ssrn= |zbl= |id= |archive-url= |archive-date= |access-date= |via= |registration= |subscription= |lay-summary= |lay-source= |lay-date= |quote= |name-list-format= |mode= |postscript= |ref=}}

Full parameter set in vertical format

Parameters	Prerequisites	Brief instructions / notes	Vertical list
last1		may also use "last"; for additional authors, "last2", "last3", etc.	{{cite book |last1= |first1= |author-link1= |author-mask1= |last2= |first2= |display-authors= |last-author-amp= |translator-last1= |translator-first1= |translator-link1= |translator-mask1= |date= |year= |orig-year= |chapter= |script-chapter= |trans-chapter= |chapter-url= |chapter-format= |editor1-last= |editor1-first= |editor1-link= |editor1-mask= |display-editors= |title= |script-title= |trans-title= |url= |dead-url= |format= |type= |series= |language= |volume= |issue= |others= |edition= |location= |publisher= |publication-date= |page= |pages= |at= |nopp= |arxiv= |asin= |bibcode= |doi= |doi-broken-date= |isbn= |issn= |jfm= |jstor= |lccn= |mr= |oclc= |ol= |osti= |pmc= |pmid= |rfc= |ssrn= |zbl= |id= |archive-url= |archive-date= |access-date= |via= |registration= |subscription= |lay-summary= |lay-source= |lay-date= |quote= |name-list-format= |mode= |postscript= |ref= }}
first1	last or last1	may also use "first"; for additional authors, "first2", "first3", etc.
author-link1	last or last1	may also use "author-link"
author-mask1	last or last1	may also use "author-mask"
last2	last1
first2	last2
display-authors	last or last1
last-author-amp	last or last1
translator-last1		may also use "translator-last"; for additional translators, "translator-last2, etc.
translator-first1	translator-last or translator-last1
translator-link1	translator-last or translator-last1
translator-mask1	translator-last or translator-last1
date
year
orig-year	year or date
chapter		This should be the title of the chapter cited. Do not wikilink "chapter" if "chapterurl" is provided
script-chapter
trans-chapter	chapter or script-chapter
chapter-url	chapter or script-chapter
chapter-format	chapter-url
editor1-last		may also use "editor-last"
editor1-first	editor1-last	may also use 'editor-first"
editor1-link	editor1-last	may also use "editor-link"
editor1-mask	editor1-last
display-editors
title
script-title
trans-title	title or script-title
url	title or script-title
dead-url
format	url
type
series
language
volume
issue
others
edition		Ordinal number
location	publisher
publisher
publication-date
page		choose one: "page", "pages", or "at"
pages		choose one: "page", "pages", or "at". Use when content on multiple pages supports the article text.
at		choose one: "page", "pages", or "at"
nopp	page or pages	set nopp to "yes" to suppress the "p." or "pp." before page numbers
arxiv
asin
bibcode
doi
doi-broken-date	doi
isbn		always include ISBN, if one has been assigned
issn
jfm
jstor
lccn
mr
oclc
ol
osti
pmc
pmid
rfc
ssrn
zbl
id
archive-url	archive-date, url
archive-date	archive-url
access-date	url
via
registration
subscription
lay-summary
lay-source	lay-summary
lay-date	lay-summary
quote
name-list-format		vanc to emulate Vancouver style
mode		cs1 or cs2
postscript
ref
If a field name is listed in the Prerequisites column it is a prerequisite for the field to the left.

Examples

Title

• {{cite book |title=Mysterious Book}}

Mysterious Book.

Title and year

• {{cite book |title=Mysterious Book |date=1901}}

Mysterious Book. 1901.

Basic usage (single author)

• {{cite book |last=Bloggs |first=Joe |authorlink=Joe Bloggs |date=1974 |title=Book of Bloggs}}

Bloggs, Joe (1974). Book of Bloggs.

Basic usage (two authors)

• {{cite book |last1=Bloggs |first1=Joe |authorlink1=Joe Bloggs |last2=Bloggs |first2=Fred |authorlink2=Fred Bloggs |date=1974 |title=Book of Bloggs}}

Bloggs, Joe; Bloggs, Fred (1974). Book of Bloggs.

Basic usage with url (and access-date) and edition

• {{cite book |last=Bloggs |first=Joe |authorlink=Joe Bloggs |date=1974 |title=Book of Bloggs |edition=1st |url=http://en.wikipedia.org/ |access-date=February 17, 2006}}

Bloggs, Joe (1974). Book of Bloggs (1st ed.). Retrieved February 17, 2006.

Citing a chapter in a book with different authors for different chapters and an editor

• {{cite book |last=Bloggs |first=Fred |editor-last=Doe |editor-first=John |title=Big Compilation Book with Many Chapters and Distinct Chapter Authors |publisher=Book Publishers |date=January 1, 2001 |pages=100–110 |chapter=Chapter 2: The History of the Bloggs Family |isbn=978-1-234-56789-7}}

Bloggs, Fred (January 1, 2001). "Chapter 2: The History of the Bloggs Family". In Doe, John (ed.). Big Compilation Book with Many Chapters and Distinct Chapter Authors. Book Publishers. pp. 100–110. ISBN 978-1-234-56789-7.

Citing a chapter in a book with two joint authors and an editor

• {{cite book |last1=Bloggs |first1=Joe |last2=Egg |first2=Fred |editor-last=Doe |editor-first=John |title=Big Book with Many Chapters and Two Co-authors |publisher=Book Publishers |date=January 1, 2001 |orig-year=1st pub. 1986 |pages=100–110 |chapter=Chapter 6: Getting There |chapterurl=http://en.wikipedia.org/ |isbn=978-1-234-56789-7 |lastauthoramp=y}}

Bloggs, Joe & Egg, Fred (January 1, 2001) [1st pub. 1986]. "Chapter 6: Getting There". In Doe, John (ed.). Big Book with Many Chapters and Two Co-authors. Book Publishers. pp. 100–110. ISBN 978-1-234-56789-7.

Three authors, title with a piped wikilink, edition

• {{cite book |last1=Bloggs |first1=Joe |authorlink1=Joe Bloggs |last2=Smith |first2=John |last3=Smythe |first3=Jim |title=[[A Thousand Acres|1000 Acres]] |edition=2nd}}

Bloggs, Joe; Smith, John; Smythe, Jim. 1000 Acres (2nd ed.).

Complex usage showing effect of using volume parameter and lastauthoramp parameter (without volume and lastauthoramp)

• {{cite book |last1=Playfair |first1=I.S.O. |authorlink1=Ian Stanley Ord Playfair |last2=Stitt |first2=G.M.S. |last3=Molony |first3=C.J.C. |last4=Toomer |first4=S.E. |editor-last=Butler |editor-first=J.R.M. |series=History of the Second World War, United Kingdom Military Series |title=Mediterranean and Middle East. Volume I: The Early Successes Against Italy (to May 1941) |publisher=Naval & Military Press |location=Uckfield, UK |date=2007 |orig-year=1st pub. [[HMSO]]:1954 |isbn=1-845740-65-3}}

Playfair, I.S.O.; Stitt, G.M.S.; Molony, C.J.C.; Toomer, S.E. (2007) [1st pub. HMSO:1954]. Butler, J.R.M. (ed.). Mediterranean and Middle East. Volume I: The Early Successes Against Italy (to May 1941). History of the Second World War, United Kingdom Military Series. Uckfield, UK: Naval & Military Press. ISBN 1-845740-65-3.

Complex usage showing effect of using volume parameter and lastauthoramp parameter (with volume and lastauthoramp)

• {{cite book |last1=Playfair |first1=I.S.O. |authorlink1=Ian Stanley Ord Playfair |last2=Stitt |first2=G.M.S. |last3=Molony |first3=C.J.C. |last4=Toomer |first4=S.E. |editor-last=Butler |editor-first=J.R.M. |series=History of the Second World War, United Kingdom Military Series |title=Mediterranean and Middle East |volume=Volume I: The Early Successes Against Italy (to May 1941) |publisher=Naval & Military Press |location=Uckfield, UK |date=2007 |orig-year=1st pub. [[HMSO]]:1954 |isbn=1-845740-65-3 |lastauthoramp=y}}

Playfair, I.S.O.; Stitt, G.M.S.; Molony, C.J.C. & Toomer, S.E. (2007) [1st pub. HMSO:1954]. Butler, J.R.M. (ed.). Mediterranean and Middle East. History of the Second World War, United Kingdom Military Series. Volume I: The Early Successes Against Italy (to May 1941). Uckfield, UK: Naval & Military Press. ISBN 1-845740-65-3.

Date without day, wikilinked title and publisher, pages, edition, location

• {{cite book |last1=Cordell |first1=Bruce R. |last2=Grubb |first2=Jeff |last3=Noonan |first3=David |date=September 2001 |title=[[Manual of the Planes]] |edition=3rd |publisher=Wizards of the Coast |location=Renton, Washington |isbn=0-7869-1850-0 |pages=134–137}}

Cordell, Bruce R.; Grubb, Jeff; Noonan, David (September 2001). Manual of the Planes (3rd ed.). Renton, Washington: Wizards of the Coast. pp. 134–137. ISBN 0-7869-1850-0.

Other language

• {{cite book |last=Bloggs |first=Jean |date=1974 |title=Livre de Bloggs |edition=1st |language=French |trans-title=Book of Bloggs |url=http://en.wikipedia.org/ |access-date=February 17, 2006}}

Bloggs, Jean (1974). Livre de Bloggs [Book of Bloggs] (in French) (1st ed.). Retrieved February 17, 2006.CS1 maint: unrecognized language (link)

Using a DOI

• {{cite book |last=Mumford |first=David |authorlink=David Mumford |date=1999 |title=The Red Book of Varieties and Schemes: Includes the Michigan Lectures (1974) on Curves and Their Jacobians |edition=2nd |publisher=Springer-Verlag |doi=10.1007/b62130 |isbn=354063293X}}

Mumford, David (1999). The Red Book of Varieties and Schemes: Includes the Michigan Lectures (1974) on Curves and Their Jacobians (2nd ed.). Springer-Verlag. doi:10.1007/b62130. ISBN 354063293X.

Using author-mask parameter

• {{cite book |last1=Playfair |first1=I.S.O. |authorlink1=Ian Stanley Ord Playfair |last2=Stitt |first2=G.M.S. |last3=Molony |first3=C.J.C. |last4=Toomer |first4=S.E. |editor-last=Butler |editor-first=J.R.M. |editor-link=James Ramsay Montagu Butler |series=History of the Second World War, United Kingdom Military Series |title=Mediterranean and Middle East Volume I: The Early Successes Against Italy (to May 1941) |publisher=Naval & Military Press |location=Uckfield, UK |date=2004 |orig-year=1st pub. [[HMSO]]:1954 |isbn=1-845740-65-3 |lastauthoramp=y}}

Playfair, I.S.O.; Stitt, G.M.S.; Molony, C.J.C. & Toomer, S.E. (2004) [1st pub. HMSO:1954]. Butler, J.R.M. (ed.). Mediterranean and Middle East Volume I: The Early Successes Against Italy (to May 1941). History of the Second World War, United Kingdom Military Series. Uckfield, UK: Naval & Military Press. ISBN 1-845740-65-3.

• {{cite book |last1=Playfair |first1=I.S.O. |authorlink1=Ian Stanley Ord Playfair |last2=Flynn |first2=F.C. |last3=Molony |first3=C.J.C. |last4=Toomer |first4=S.E. |editor-last=Butler |editor-first=J.R.M. |editor-link=James Ramsay Montagu Butler |series=History of the Second World War, United Kingdom Military Series |title=The Mediterranean and Middle East, Volume II: The Germans Come to the Help of Their Ally (1941) |publisher=Naval & Military Press |location=Uckfield, UK |date=2004 |orig-year=1st pub. [[HMSO]]:1954 |isbn=1-845740-66-1 |lastauthoramp=y |author-mask=2}}

——; Flynn, F.C.; Molony, C.J.C. & Toomer, S.E. (2004) [1st pub. HMSO:1954]. Butler, J.R.M. (ed.). The Mediterranean and Middle East, Volume II: The Germans Come to the Help of Their Ally (1941). History of the Second World War, United Kingdom Military Series. Uckfield, UK: Naval & Military Press. ISBN 1-845740-66-1.

• {{cite book |last1=Playfair |first1=I.S.O. |authorlink1=Ian Stanley Ord Playfair |last2=Flynn |first2=F.C. |last3=Molony |first3=C.J.C. |last4=Gleave |first4=T.P. |editor-last=Butler |editor-first=Sir James |editor-link=James Ramsay Montagu Butler |series=History of the Second World War, United Kingdom Military Series |title=The Mediterranean and Middle East, Volume III: British Fortunes Reach Their Lowest Ebb (September 1941 to September 1942) |publisher=Naval & Military Press |location=Uckfield, UK |date=2004 |orig-year=1st pub. [[HMSO]]:1954 |isbn=1-845740-67-X |lastauthoramp=y |author-mask=2}}

——; Flynn, F.C.; Molony, C.J.C. & Gleave, T.P. (2004) [1st pub. HMSO:1954]. Butler, Sir James (ed.). The Mediterranean and Middle East, Volume III: British Fortunes Reach Their Lowest Ebb (September 1941 to September 1942). History of the Second World War, United Kingdom Military Series. Uckfield, UK: Naval & Military Press. ISBN 1-845740-67-X.

Using display-authors parameter

• {{cite book |last1=Playfair |first1=I.S.O. |authorlink1=Ian Stanley Ord Playfair |last2=Stitt |first2=G.M.S. |last3=Molony |first3=C.J.C. |last4=Toomer |first4=S.E. |editor-last=Butler |editor-first=J.R.M. |editor-link=James Ramsay Montagu Butler |series=History of the Second World War, United Kingdom Military Series |title=Mediterranean and Middle East Volume I: The Early Successes Against Italy (to May 1941) |publisher=Naval & Military Press |location=Uckfield, UK |date=2004 |orig-year=1st pub. [[HMSO]]:1954 |isbn=1-845740-65-3 |display-authors=1}}

Playfair, I.S.O.; et al. (2004) [1st pub. HMSO:1954]. Butler, J.R.M. (ed.). Mediterranean and Middle East Volume I: The Early Successes Against Italy (to May 1941). History of the Second World War, United Kingdom Military Series. Uckfield, UK: Naval & Military Press. ISBN 1-845740-65-3.

Parameters

Syntax

Nested parameters rely on their parent parameters:

• parent
• OR: parent2—may be used instead of parent
  • child—may be used with parent (and is ignored if parent is not used)
  • OR: child2—may be used instead of child (and is ignored if parent2 is not used)

Where aliases are listed, only one of the parameters may be defined; if multiple aliased parameters are defined, then only one will show.

COinS

This template embeds COinS metadata in the HTML output, allowing reference management software to retrieve bibliographic metadata. As a general rule, only one data item per parameter. Do not include explanatory or alternate text:

• Use |date=27 September 2007 not |date=27 September 2007 (print version 25 September)

Use of templates within the citation template is discouraged because many of these templates will add extraneous HTML or CSS that will be included raw in the metadata. Also, HTML entities, for example  , –, etc, should not be used in parameters that contribute to the metadata. Do not include Wiki markup '' (italic font) or ''' (bold font) because these markup characters will contaminate the metadata.

COinS metadata is created for these parameters

• |periodical=, |journal=, |newspaper=, |magazine=, |work=, |website=, |encyclopedia=, |encyclopaedia=, |dictionary=
• |chapter=, |contribution=, |entry=, |article=, |section=
• |title=
• |publication-place=, |publicationplace=, |place=, |location=
• |date=, |year=, |publication-date=, |publicationdate=
• |series=, |version=
• |volume=
• |issue=, |number=
• |page=, |pages=, |at=
• |edition=
• |publisher=, |distributor=, |institution=
• |url=
• |chapter-url=, |chapterurl=, |contribution-url=, |contributionurl=, |section-url=, |sectionurl=
• |author#=, |author-last#=, |author#-last=, |last#=, |surname#=
• |author-first#=, |author#-first=, |first#=, |given#=
• any of the named identifiers (|isbn=, |issn=, |doi=, |pmc=, etc)

Deprecated

{{#lst:Help:CS1 errors|deprecated_params_table }}

Description

Authors

• last: Surname of a single author. Do not wikilink—use author-link instead. For corporate authors or authors for whom only one name is listed by the source, use last or one of its aliases (e.g. |author=Bono). Aliases: surname, author, last1, surname1, author1.
  • author: this parameter is used to hold the complete name of a single author (first and last) or to hold the name of a corporate author. This parameter should never hold the names of more than one author.
  • first: Given or first names of author; for example: Firstname Middlename or Firstname M. or Firstname M., Sr. Do not wikilink—use author-link instead. Aliases: given, first1, given1. Requires last; first name will not display if last is empty.
  • OR: for multiple authors, use last1, first1 through lastn, firstn, where n is any consecutive number for an unlimited number of authors (each firstn requires a corresponding lastn, but not the other way around). Aliases: surname1, given1 through surnamen, givenn, or author1 through authorn. For an individual author plus an institutional author, you can use |first1=...|last1=...|author2=....
  • author-link: Title of existing Wikipedia article about the author—not the author's website; do not wikilink. Aliases: author-link1, authorlink, authorlink1, author1-link, author1link.
  • OR: for multiple authors, use author-link1 through author-linkn. Aliases: authorlink1 through authorlinkn, or author1-link through authorn-link, or author1link through authornlink.
  • name-list-format: displays authors and editors in Vancouver style when set to vanc and when the list uses last/first parameters for the name list(s).
• vauthors: comma-separated list of author names in Vancouver style; enclose corporate or institutional author names in doubled parentheses:

  |vauthors=Smythe JB, ((Megabux Corp.))

  • author-link and author-mask may be used for the individual names in |vauthors= as described above
• authors: Free-form list of author names; use of this parameter is discouraged because it does not contribute to a citation's metadata; not an alias of last.
• contributor-last: (book cites only) surname of the author of contribution (which is required). Aliases: contributor-surname, contributor1, contributor1-last, contributor-last1.
  • contributor-first: Given or first names of contributor. Do not wikilink—use contributor-link instead. Aliases: contributor-given, contributor1-first, contributor-first1.
  • OR: for multiple contributors, use contributor-last1, contributor-first1 through contributor-lastn, contributor-firstn where n is any consecutive number for an unlimited number of contributors (each contributor-firstn requires a corresponding contributor-lastn, but not the other way around). Aliases: contributor1-last, contributor1-first through contributorn-last, contributorn-first, or contributor1 through contributorn.
  • contributor-link: Title of existing Wikipedia article about the contributor—not the contributor's website; do not wikilink. Aliases: contributor-link1, contributor1-link.
  • OR: for multiple contributors, use contributor-link1 through contributor-linkn. Aliases: contributor1-link through contributorn-link.
• translator-last: Surname of translator. Do not wikilink—use translator-link instead. Aliases: translator-surname, translator1, translator1-last, translator-last1.
  • translator-first: Given or first names of translator. Do not wikilink—use translator-link instead. Aliases: translator-given, translator1-first, translator-first1.
  • OR: for multiple translators, use translator-last1, translator-first1 through translator-lastn, translator-firstn, where n is any consecutive number for an unlimited number of translators (each translator-firstn requires a corresponding translator-lastn, but not the other way around). Aliases: translator1-last, translator1-first through translatorn-last, translatorn-first, or translator1 through translatorn.
  • translator-link: Title of existing Wikipedia article about the translator—not the translator's website; do not wikilink. Aliases: translator-link1, translator1-link.
  • OR: for multiple translators, use translator-link1 through translator-linkn. Aliases: translator1-link through translatorn-link.
• collaboration: Name of a group of authors or collaborators; requires author, last, or vauthors listing one or more primary authors; follows author name-list; appends "et al." to author name-list.
• others: To record other contributors to the work, including illustrators. For the parameter value, write Illustrated by John Smith.
• Note: When using shortened footnotes or parenthetical referencing styles with templates, do not use multiple names in one field, or else the anchor will not match the inline link.

Title

• title: Title of source. Can be wikilinked to an existing Wikipedia article or url may be used to add an external link, but not both. Displays in italics. If script-title is defined, title holds romanized transliteration of title in script-title.
  • script-title: Original title for languages that do not use a Latin-based alphabet (Arabic, Chinese, Cyrillic, Greek, Hebrew, Japanese, Korean, Vietnamese, etc); not italicized, follows italicized transliteration defined in title. May be prefixed with an ISO 639-1 two-character code to help browsers properly display the script:

    ... |title=Tōkyō tawā |script-title=ja:東京タワー |trans-title=Tokyo Tower ...

  • trans-title: English translation of the title if the source cited is in a foreign language. Displays in square brackets after title; if url is defined, then trans-title is included in the link. Use of the language parameter is recommended.

Titles containing certain characters will not display and link correctly unless those characters are encoded.

newline	[	]	|
space	[	]	{{!}} (preferred)
	{{bracket|text}}		| or {{pipe}} –

• title-link: Title of existing Wikipedia article about the source named in title – do not use a web address; do not wikilink. Alias: titlelink.

• type: Provides additional information about the media type of the source. May alternatively be used to identify the type of manuscript linked to in the title, if this is not the final version of a manuscript (e.g. if a preprint of a manuscript is freely available, but the version of record is behind a paywall). Format in sentence case. Displays in parentheses following the title. Examples: Thesis, Booklet, Accepted manuscript, CD liner, Press release. Alias: medium.

• chapter: The chapter heading of the source. May be wikilinked or may use chapter-url, but not both. Displays in quotes.
  • script-chapter: Chapter heading for languages that do not use a Latin-based alphabet (Arabic, Chinese, Cyrillic, Greek, Hebrew, Japanese, Korean, Vietnamese, etc); follows transliteration defined in chapter. Should be prefixed with an ISO 639-1 two-character code to help browsers properly display the script:

    ... |chapter=Tōkyō tawā |script-chapter=ja:東京タワー |trans-chapter=Tokyo Tower ...

  • trans-chapter: English translation of the chapter heading, if the source cited is in a foreign language. Displays in square brackets after the chapter field; if chapter-url is defined, then trans-chapter is included in the link. Use of the language parameter is recommended.
• contribution: A separately-authored part of author's book. May be wikilinked or may use contribution-url, but not both. Values of Afterword, Foreword, Introduction, or Preface will display unquoted; any other value will display in quotation marks. The author of the contribution is given in contributor.

• language: The language in which the source is written. Displays in parentheses with "in" before the language name or names. Use the full language name or the proper language code (list of supported codes / names). When the source uses more than one language, list them individually, separated by commas, e.g. |language=French, German. The use of language names or language codes recognized by Wikimedia adds the page to the appropriate subcategory of Category:CS1 foreign language sources; do not use templates or wikilinks. Note: When the language is "English" (or "en"), no language is displayed in the citation. Note: When two or more languages are listed there is no need to include "and" before the last language. "and" is inserted automatically by the template. Aliases: lang

Date

• date: Date of source being referenced. Can be full date (day, month, and year) or partial date (month and year, season and year, or year). Use same format as other publication dates in the citations. Required when year is used to disambiguate {{sfn}} links to multiple-work citations by the same author in the same year.^[more] Do not wikilink. Displays after the authors and is enclosed in parentheses. If there is no author, then displays after publisher.

For approximate year, precede with "c. ", like this: |date=c. 1900.

For no date, or "undated", use |date=n.d.

• year: Year of source being referenced. Use of |date= is recommended unless all of the following conditions are met:
  1. The |date= format is YYYY-MM-DD.
  2. The citation requires a CITEREF disambiguator.
  3. The template uses |ref=harv or |mode=cs2, or the template is {{citation}}.
• orig-year: Original publication year; displays in square brackets after the date (or year). For clarity, please supply specifics. For example: |orig-year=First published 1859 or |orig-year=Composed 1904. Alias: origyear
• df: date format; sets rendered dates to the specified format; does not support date ranges or seasonal dates. Accepts one value which may be one of these:

  dmy – set publication dates to day month year format; access- and archive-dates are not modified;

  mdy – as above for month day, year format

  ymd – as above for year initial numeric format YYYY-MM-DD

  dmy-all – set publication, access-, and archive-dates to day month year format;

  mdy-all – as above for month day, year format

  ymd-all – as above for year initial numeric format YYYY-MM-DD

Publisher

• publisher: Name of publisher; may be wikilinked if relevant. The publisher is the company that publishes the work being cited. Do not use the publisher parameter for the name of a work (e.g. a website, book, encyclopedia, newspaper, magazine, journal, etc.). Corporate designations such as "Ltd", "Inc.", or "GmbH" are not usually included. Not normally used for periodicals. Omit where the publisher's name is substantially the same as the name of the work (for example, The New York Times Co. publishes The New York Times newspaper, so there is no reason to name the publisher). Displays after title.
• place: For news stories with a byline, that is, the location where the story was written. In earlier versions of the template this was the publication place, and for compatibility, will be treated as the publication place if the publication-place parameter is absent; see that parameter for further information. Alias: location
• publication-place: Geographical place of publication; generally not wikilinked; omit when the name of the work includes the publication place; examples: The Boston Globe, The Times of India. Displays after the title. If only one of publication-place, place, or location is defined, it will be treated as the publication place and will show after the title; if publication-place and place or location are defined, then place or location is shown before the title prefixed with "written at" and publication-place is shown after the title.
• publication-date: Date of publication when different from the date the work was written. Displays only if year or date are defined and only if different, else publication-date is used and displayed as date. Use the same format as other dates in the article; do not wikilink. Follows publisher; if work is not defined, then publication-date is preceded by "published" and enclosed in parenthesis.
• via: Name of the content deliverer (if different from publisher). via is not a replacement for publisher, but provides additional detail. It may be used when the content deliverer presents the source in a format other than the original (e.g. NewsBank), when the URL provided does not make clear the identity of the deliverer, where no URL or DOI is available (EBSCO), or if the deliverer requests attribution.

Edition, series, volume

• edition: When the publication has more than one edition; for example: "2nd", "Revised", and so forth. Appends the string " ed." after the field, so |edition=2nd produces "2nd ed." Does not display if a periodical field is defined.

• series or version: When the source is part of a series, such as a book series or a journal where the issue numbering has restarted.

• volume: For one publication published in several volumes. Displays after the title and series fields; volume numbers should be entered just as a numeral (e.g. 37); volume values that are wholly digits, wholly uppercase roman numerals, or less than five characters will appear in bold. Any non-numeric value of five or more characters will be presumed to follow some other convention and will not appear in bold.

In-source locations

• page: The number of a single page in the source that supports the content. Use either |page= or |pages=, but not both. Displays preceded by <syntaxhighlight lang="text" class="" id="" style="" inline="1">p.</syntaxhighlight> unless |nopp=y.
• OR: pages: A range of pages in the source that supports the content. Use either |page= or |pages=, but not both. Separate using an en dash (–); separate non-sequential pages with a comma (,); do not use to indicate the total number of pages in the source. Displays preceded by <syntaxhighlight lang="text" class="" id="" style="" inline="1">pp.</syntaxhighlight> unless |nopp=y. Hyphens are automatically converted to en dashes; if hyphens are appropriate, for example: pp. 3-1–3-15, use |pages=3{{hyphen}}1–3{{hyphen}}15 or |at=pp. 3-1–3-15.
  • nopp: Set to y, yes, or true to suppress the <syntaxhighlight lang="text" class="" id="" style="" inline="1">p.</syntaxhighlight> or <syntaxhighlight lang="text" class="" id="" style="" inline="1">pp.</syntaxhighlight> notations where this is inappropriate; for example, where |page=Front cover or |pages=passim.
• OR: at: For sources where a page number is inappropriate or insufficient. Overridden by |page= or |pages=. Use only one of |page=, |pages=, or |at=.

Examples: page (p.) or pages (pp.); section (sec.), column (col.), paragraph (para.); track; hours, minutes and seconds; act, scene, canto, book, part, folio, stanza, back cover, liner notes, indicia, colophon, dust jacket, verse.

URL

• url: URL of an online location where the text of the publication can be found. Cannot be used if title is wikilinked. If applicable, the link may point to the specific page(s) referenced. Remove tracking parameters from URLs, e.g. #ixzz2rBr3aO94 or ?utm_source=google&utm_medium=...&utm_term=...&utm_campaign=.... Do not link to any commercial booksellers, such as Amazon.com; use |ISBN= or |OCLC= to provide neutral search links for books. Invalid URLs, including those containing spaces, will result in an error message.
  • access-date: Full date when the content pointed to by url was last verified to support the text in the article; do not wikilink; requires url; use the same format as other access and archive dates in the citations. Not required for linked documents that do not change. For example, access-date is required for online sources, such as personal websites, that do not have a publication date; see WP:CITEWEB. Access dates are not required for links to published research papers, published books, or news articles with publication dates. Note that access-date is the date that the URL was found to be working and to support the text being cited. Can be hidden or styled by registered editors. Alias: accessdate.
  • archive-url: The URL of an archived snapshot of a web page. Typically used to refer to services such as Internet Archive , WebCite and archive.is ; requires archive-date and url. By default (overridden by |url-status=live, or the equivalent |dead-url=no, deprecated but still used in many articles) the archived link is displayed first, with the original link at the end. Alias: archiveurl.
    • archive-date: Archive-service snapshot-date; preceded in display by default text "archived from the original on". Use the same format as other access and archive dates in the citations. This does not necessarily have to be the same format that was used for citing publication dates. Do not wikilink; templated dates are discouraged. Alias: archivedate.
    • url-status: this optional parameter is ignored if archive-url is not set. If omitted, or with null value, the default value is |url-status=dead. When the URL is still live, but pre-emptively archived, then set |url-status=live; this changes the display order, with the title retaining the original link and the archive linked at the end. When the original URL has been usurped for the purposes of spam, advertising, or is otherwise unsuitable, setting |url-status=unfit or |url-status=usurped suppresses display of the original URL (but |url= and |archive-url= are still required).
    • dead-url: (deprecated) the default value of this optional parameter, if omitted, is |dead-url=yes; equivalent values are y or true. Ignored if archive-url is not set. When the URL is still live, but pre-emptively archived, then set |dead-url=no; this changes the display order, with the title retaining the original link and the archive linked at the end. When the original URL has been usurped for the purposes of spam, advertising, or is otherwise unsuitable, setting |dead-url=unfit or |dead-url=usurped suppresses display of the original URL (but |url= and |archive-url= are still required). Alias: deadurl (deprecated).
  • template-doc-demo: The archive parameters will be error-checked to ensure that all the required parameters are included, or else {{citation error}} is invoked. With errors, main, help and template pages are placed into one of the subcategories of Category:Articles with incorrect citation syntax. Set |template-doc-demo=true to disable categorization; mainly used for documentation where the error is demonstrated. Alias: no-cat.
• format: Format of the work referred to by url; for example: PDF, DOC, or XLS; displayed in parentheses after title. (For media format, use type.) HTML is implied and should not be specified. Automatically added when a PDF icon is displayed. Does not change the external link icon. Note: External link icons do not include alt text; thus, they do not add format information for the visually impaired.

URLs must begin with a supported URI scheme. http:// and https:// will be supported by all browsers; however, ftp://, gopher://, irc://, ircs://, mailto: and news: may require a plug-in or an external application and should normally be avoided. IPv6 host-names are currently not supported.

If URLs in citation template parameters contain certain characters, then they will not display and link correctly. Those characters need to be percent-encoded. For example, a space must be replaced by %20. To encode the URL, replace the following characters with:

sp	"	'	<	>	[	]	{	|	}
%20	%22	%27	%3c	%3e	%5b	%5d	%7b	%7c	%7d

Single apostrophes do not need to be encoded; however, unencoded multiples will be parsed as italic or bold markup. Single curly closing braces also do not need to be encoded; however, an unencoded pair will be parsed as the double closing braces for the template transclusion.

Chapter URL

• chapter-url: URL of an individual chapter of online source. Should be at the same site as url, if any. If chapter-url is used, url should only be used if the beginning of the work and the cited chapter are on separate webpages at the site. chapter may be wikilinked or chapter-url used, but not both. Aliases: chapterurl, contribution-url, section-url.
• chapter-format: Format of the work referred to by chapter-url; for example: PDF, DOC, or XLS; displayed in parentheses after chapter. HTML is implied and should not be specified. Does not change the external link icon. Note: External link icons do not include alt text; thus, they do not add format information for the visually impaired.

Anchor

• ref: the citation's HTML anchor identifier. When set, |ref=ID generates an anchor with the given ID (the id attribute in the citation's <cite id="ID"> HTML tag). Setting |ref=ID identifies the template as a target and allows wikilinking to full references, especially useful with short-form citations like shortened notes and parenthetical referencing. The special value |ref=harv generates an anchor identifier suitable for use with {{sfn}} and {{harv}} templates. For |mode=cs2 |ref= defaults to |ref=harv.

Identifiers

• id: A unique identifier, used where none of the specialized identifiers are applicable; wikilink or use a template as applicable. For example, |id=NCJ 122967 will append "NCJ 122967" at the end of the citation. You can use templates such as |id={{NCJ|122967}} to append NCJ 122967 instead.

These identifiers create links and are designed to accept a single value. Using multiple values or other text will break the link and/or invalidate the identifier. In general, the parameters should include only the variable part of the identifier, e.g. rfc=822 or pmc=345678.

When an URL is equivalent to the link produced by the corresponding identifier (such as a DOI), don't add it to any URL parameter but use the appropriate identifier parameter, which is more stable and may allow to specify the access status. The |url= parameter or title link can then be used for its prime purpose of providing a convenience link to an open access copy which would not otherwise be obviously accessible.

• arxiv: arXiv identifier; for example: arxiv=hep-th/9205027 (before April 2007) or arxiv=0706.0001 (April 2007 – December 2014) or arxiv=1501.00001 (since January 2015). Do not include extraneous file extensions like ".pdf" or ".html".
• asin: Amazon Standard Identification Number; if first character of asin value is a digit, use isbn. Because this link favours one specific distributor, include it only if standard identifiers are not available. Example asin=B00005N5PF
  • asin-tld: ASIN top-level domain for Amazon sites other than the US; valid values: au, br, ca, cn, co.jp, co.uk, de, es, fr, it, mx
• bibcode: Bibcode; used by a number of astronomical data systems; for example: 1974AJ.....79..819H. Comment: Techies are aware of the 2019 switch from old to new ADS URLs: the old URLs should continue working after October 2019 even though deprecated; see the April/May 2019 and June 2019 discussions.
• biorxiv: bioRxiv id, a 6-digit number at the end of the biorXiv URL (e.g. 078733 for http://biorxiv.org/content/early/2016/10/01/078733 or https://dx.doi.org/10.1101/078733)
• citeseerx: CiteSeerX id, a string of digits and dots found in a CiteSeerX URL (e.g. 10.1.1.176.341 for http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.176.341 )
• doi: Digital object identifier; for example: 10.1038/news070508-7. It is checked to ensure it begins with (<syntaxhighlight lang="text" class="" id="" style="" inline="1">10.</syntaxhighlight>).
  • doi-broken-date: Date the DOI was found to be non-working at https://dx.doi.org. Use the same format as other dates in the article. Alias: doi-inactive-date
• eissn: International Standard Serial Number for the electronic media of a serial publication; eight characters may be split into two groups of four using a hyphen, but not an en dash or a space; example eissn=1557-2986 Alias: EISSN
• hdl: Handle System identifier for digital objects and other resources on the Internet; example hdl=20.1000/100 Alias: HDL
• isbn: International Standard Book Number; for example: 978-0-8126-9593-9. Hyphens in the ISBN are optional, but preferred. Use the ISBN actually printed on or in the book. Use the 13-digit ISBN – beginning with 978 or 979 – when it is available. If only a 10-digit ISBN is printed on or in the book, use it. ISBNs can be found on the page with the publisher's information – usually the back of the title page – or beneath the barcode as a number beginning with 978 or 979 (barcodes beginning with any other numbers are not ISBNs). For sources with the older 9-digit SBN system, prefix the number with a zero; thus, SBN 902888-45-5 should be entered as |isbn=0-902888-45-5. Do not convert a 10-digit ISBN to 13-digit by just adding the 978 prefix; the last digit is a calculated check digit and just making changes to the numbers will make the ISBN invalid. This parameter should hold only the ISBN without any additional characters. It is checked for length, invalid characters – anything other than numbers, spaces, and hyphens, with "X" permitted as the last character in a 10-digit ISBN – and the proper check digit. Alias: ISBN
• ismn: International Standard Music Number; for example: 979-0-9016791-7-7. Hyphens or spaces in the ISMN are optional. Use the ISMN actually printed on or in the work. This parameter should hold only the ISMN without any additional characters. It is checked for length, invalid characters – anything other than numbers, spaces, and hyphens – and the proper check digit. Alias: ISMN
• issn: International Standard Serial Number; eight characters may be split into two groups of four using a hyphen, but not an en dash or a space; example issn=2049-3630 Alias: ISSN
• jfm: Jahrbuch über die Fortschritte der Mathematik; example jfm=53.0144.01
• jstor: JSTOR reference number; for example: jstor=3793107 will generate JSTOR 3793107.
• lccn: Library of Congress Control Number. When present, alphabetic prefix characters are to be lower case; example lccn=2004042477
• mr: Mathematical Reviews; example mr=630583
• oclc: OCLC; WorldCat's Online Computer Library Center; example oclc=9355469
• ol: Open Library identifier; do not include "OL" in the value; example ol=7030731M
• osti: Office of Scientific and Technical Information; example osti=4367507
• pmc: PubMed Central; use article number for open repository full-text of a journal article, e.g. pmc=345678. Do not include "PMC" in the value.
  • embargo: Date that pmc goes live; if this date is in the future, then pmc is not linked until that date.
• pmid: PubMed; use unique identifier; example pmid=17322060
• rfc: Request for Comments; example rfc=3143
• ssrn: Social Science Research Network; example ssrn=1900856
• zbl: Zentralblatt MATH; example zbl=0472.53010 For zbMATH search results like JFM 35.0387.02 use jfm=35.0387.02

Quote

• quote: Relevant text quoted from the source. Displays enclosed in quotes. When supplied, the citation terminator (a period by default) is suppressed, so the quote must include terminating punctuation.

Editors

• editor-last: Surname of editor. Do not wikilink—use editor-link instead. Where the surname is usually written first—as in Chinese—or for corporate authors, simply use editor-last to include the same format as the source. Aliases: editor-last1, editor1-last, editor-surname, editor-surname1, editor1-surname, editor, editor1.
  • editor: this parameter is used to hold the complete name of a single editor (first and last), or the name of an editorial committee. This parameter should never hold the names of more than one editor.
  • editor-first: Given or first names of editor, including title(s); example: Firstname Middlename or Firstname M. or Dr. Firstname M., Sr. Do not wikilink—use editor-link instead. Aliases: editor-first1, editor1-first, editor-given, editor-given1, editor1-given.
  • OR: for multiple editors, use editor-last1, editor-first1 through editor-lastn, editor-firstn (Aliases: editorn-last, editor-surnamen or editorn-surname; editorn-first, editor-givenn or editorn-given; editorn). For an individual editor plus an institutional editor, you can use |editor-first1=...|editor-last1=... |editor2=....

• editor-link: Title of existing Wikipedia article about the editor—not the editor's website; do not wikilink. Aliases: editor-link1.
• OR: for multiple editors, use editor-link1 through editor-linkn (alias editorn-link).
• name-list-format: displays authors and editors in Vancouver style when set to vanc and when the list uses last/first parameters for the name list(s)

• veditors: comma separated list of editor names in Vancouver style; enclose corporate or institutional names in doubled parentheses:

  |veditors=Smythe JB ((Megabux Corp.))

• editor-linkn and editor-maskn may be used for the individual names in |veditors=, as described above

• editors: Free-form list of editor names; use of this parameter is discouraged; not an alias of editor-last

Display:

Use display-editors to control the length of the displayed editor name list and to specify when "et al." is included.

If authors: Authors are first, followed by the included work, then "In" and the editors, then the main work.

If no authors: Editors appear before the included work; a single editor is followed by "ed."; multiple editors are followed by "eds."

Laysummary

• lay-url: URL link to a non-technical summary or review of the source; the URL title is set to "Lay summary". Aliases: lay-summary (deprecated), laysummary (deprecated).
  • lay-source: Name of the source of the laysummary. Displays in italics and preceded by an endash. Alias: laysource.
  • lay-date: Date of the summary. Displays in parentheses. Alias: laydate.

Display options

• mode: Sets element separator, default terminal punctuation, and certain capitalization according to the value provided. For |mode=cs1, element separator and terminal punctuation is a period (.); where appropriate, initial letters of certain words are capitalized ('Retrieved...'). For |mode=cs2, element separator is a comma (,); terminal punctuation is omitted; where appropriate, initial letters of certain words are not capitalized ('retrieved...'). To override default terminal punctuation use postscript.
• author-mask: Replaces the name of the first author with em dashes or text. Set author-mask to a numeric value n to set the dash n em spaces wide; set author-mask to a text value to display the text without a trailing author separator; for example, "with". You must still include the values for all authors for metadata purposes. Primarily intended for use with bibliographies or bibliography styles where multiple works by a single author are listed sequentially such as shortened footnotes. Do not use in a list generated by {{reflist}}, <references /> or similar as there is no control of the order in which references are displayed. You can also use editor-mask and translator-mask in the same way. Mask parameters can take a number in the name of the parameter (e.g. |authorn-mask=) to specify which author the mask should apply to.
• display-authors: Controls the number of author names that are displayed when a citation is published. To change the displayed number of authors, set display-authors to the desired number. For example, |display-authors=2 will display only the first two authors in a citation. By default, all authors are displayed. |display-authors=etal displays all authors in the list followed by et al. Aliases: displayauthors.
• display-editors: Controls the number of editor names that are displayed when a citation is published. To change the displayed number of editors, set display-editors to the desired number. For example, |display-editors=2 will display only the first two editors in a citation. By default, all editors are displayed. |display-editors=etal displays all editors in the list followed by et al. Aliases: displayeditors.
• last-author-amp: Switches the separator between the last two names of the author list to space ampersand space ( & ) when set to y, yes, or true. Example: |last-author-amp=yes
• postscript: Controls the closing punctuation for a citation; defaults to a period (.); for no terminating punctuation, specify |postscript=none – leaving |postscript= empty is the same as omitting it, but is ambiguous. Additional text or templates beyond the terminating punctuation may generate an error message. |postscript= is ignored if quote is defined.

Subscription or registration required

Tracked in Phabricator
Task T225430

Citations of online sources that require registration or a subscription are acceptable in Wikipedia as documented in Verifiability § Access to sources. As a courtesy to readers and other editors, editors should signal the access restrictions of the external links included in a citation. : access icons do not display correctly for editors who use Modern skin.

Four access levels can be used:

• Freely accessible free: the source is free to read for anyone (this applies in particular to articles in open access)
• Free registration required registration: a free registration is required to access the source
• Free access subject to limited trial, subscription normally required limited: there are other constraints (such as a cap on daily views) to freely access this source
• Paid subscription required subscription: the source is only accessible via a paid subscription ("paywall")

As there are often multiple external links with different access levels in the same citation, these values are attributed to a particular external link.

Access indicators for url-holding parameters

Sources linked by |url=, |chapter-url=, |entry-url=, |article-url=, and |section-url= are presumed to be free-to-read. When they are not free-to-read, editors should mark those sources with the matching access-indicator parameter so that an appropriate icon is included in the rendered citation. Because the sources linked by these url-holding parameters are presumed to be free-to-read, they may not be marked as free.

url-holding and access-indicator parameters

url	access	allowed keywords
|url=	|url-access=	registration Free registration required limited Free access subject to limited trial, subscription normally required subscription Paid subscription required
|article-url=	|article-url-access=
|chapter-url=	|chapter-url-access=
|contribution-url=	|chapter-url-access=File:Dagger-14-plain.png
|entry-url=	|entry-url-access=
|section-url=	|section-url-access=

File:Dagger-14-plain.png|contribution-url-access= not currently defined; use its alias |chapter-url-access=

Access indicators for named identifiers

Links inserted by named identifiers are presumed to lie behind a paywall or registration barrier – exceptions listed below. When they are free-to-read, editors should mark those sources with the matching access-indicator parameter so that an appropriate icon is included in the rendered citation. Because the sources linked by these named-identifier parameters are not presumed to be free-to-read, they may not be marked as limited, registration, or subscription.

named-identifier and access-indicator parameters

identifier	access	allowed keywords
|bibcode=	|bibcode-access=	free Freely accessible
|doi=	|doi-access=
|hdl=	|hdl-access=File:Dagger-14-plain.png
|jstor=	|jstor-access=
|ol=	|ol-access=
|osti=	|osti-access=

Some named-identifiers are always free-to-read. For those named-identifiers there are no access-indicator parameters, the access level is automatically indicated by the template. These named identifiers are:

• |arxiv=
• |biorxiv=
• |citeseerx=
• |pmc=
• |rfc=
• |ssrn=

Ambiguous access parameters

The parameters |registration=yes and |subscription=yes can also be used to indicate the access level of a citation. However, they do not indicate which link they apply to, so editors are encouraged to use |url-access=registration and |url-access=subscription instead, when the restriction applies to |url=. If the restriction applies to an identifier, these parameters should be omitted.

These parameters add a link note to the end of the citation:

• registration: (deprecated) For online sources that require registration, set |registration=yes (or y, or true); yields to subscription if both are set. Use the appropriate access-indicator parameter
• subscription: (deprecated) For online sources that require a subscription, set |subscription=yes (or y, or true); supersedes registration if both are set. Use the appropriate access-indicator parameter

Setting |registration= or |subscription= to any value other than y, yes, or true will generate an error message.

TemplateData

See Template:Cite book/TemplateData.

See also

• Reftag, tool for translating Google Books permalinks into Wikipedia references

This template produces COinS metadata; see COinS in Wikipedia for background information.