Wikidata:WikiProject Stanford Libraries/Sourcing statements via references

Each statement for an item may have one or more references citing a source for the information. These references may be structured in several different ways.

Wikidata reference policies edit

Statements that don't need sources edit

Common knowledge that is generally undisputed
Identifiers that link to the identifier source
Information about an object sourced from the object itself (e.g., bibliographic description for a book item taken directly from the book itself)

What constitutes a source edit

Wikidata considers an "authoritative" source to be one deemed trustworthy, up-to-date, and free of bias
Possible authoritative sources of information include:
- books (novels, textbooks, encyclopedias, atlases, guidebooks, etc.)
- academic, scientific, and industry publications (journal articles, theses, dissertations, trade magazines, conference proceedings, etc.)
- news sources (newspaper articles, radio and television news broadcasts, etc.)
- policy and legislation (including government and international organization reports)
- media (radio and television scripted series, movies, songs and music recordings, etc.)
Sources may be physical or digital
Sources may be freely available or behind a paywall (freely accessible sources preferred)
Sources should be available for others to confirm in some way (i.e., published, recorded, or in an archive), rather than an unrecorded conversation or an personal email not in an institutional archive
Wikipedia articles are not considered sources (though they may contain references that can serve as sources)
If a statement has an imported from Wikimedia project (P143) reference that can be replaced with an actual source, the imported from Wikimedia project (P143) reference may be deleted

Creating references edit

Reference properties edit

Property	Description	Example
reference URL (P854)	A link to an online source	<reference URL> http://catalogue.bnf.fr/ark:/12148/cb11953887q
retrieved (P813)	The date a source was consulted	<retrieved> 2019-07-30
language of work or name (P407)	The language of the consulted source	<language of work or name> English
stated in (P248)	The Wikidata item for the consulted source	<stated in> Internet Movie Database (Q37312)
archive URL (P1065)	Archived version of an online source	<archive URL> http://web.archive.org/web/20171111182830/https://www.alexa.com/siteinfo/imdb.com/
archive date (P2960)	Date the archived version of an online source was crawled	<archive date> 2017-02-15
quotation (P1683)	A quotation from the cited source	<quote> Mary Shelley started writing Frankenstein in the summer of 1815.
page(s) (P304)	The page number(s) of the reference	<page(s)> 15-16
column (P3903)	The column number of the reference	<column> 5
chapter (P792)	The chapter of the reference	<chapter> 7
section, verse, paragraph, or clause (P958)	Other section designation for the reference	<section, verse, paragraph, or clause> Section V, Paragraph 12
inferred from (P3452)	Wikidata item from which the statement was inferred	<inferred from> Young Frankenstein (Q651923) (e.g. for statement that Young Frankenstein is a derivative work of Frankenstein)
based on heuristic (P887)	Rule used to derive the value	<based on heuristic> inferred from matronymic name (Q69266692) (as a source for a person's gender)
Wikimedia import URL (P4656)	URL referencing a page in a Wikimedia project (including Wikidata)	<Wikimedia import URL> https://www.wikidata.org/wiki/Q65940459#P2454, https://www.wikidata.org/wiki/Property:P2454#P2302
subject named as (P1810)	The name by which the source refers to the item	<named as> Wm. Shakespeare
property for an identifier used within the source	Used with <stated in> an online source that assigns unique identifiers	<stated in> Virtual International Authority File (Q54919); VIAF ID (P214) 185508590

Citing a web page edit

Any combination of the following methods may be used to cite an online source.

Direct, live link: reference URL (P854), retrieved (P813), language of work or name (P407)
Archived link: archive URL (P1065), archive date (P2960)
Wikidata item for page: stated in (P248), retrieved (P813), source identifier property
Other properties: quotation (P1683), subject named as (P1810)

Citing an article edit

Information pertaining to the article citation (publication, issue, page numbers, link to an online article, etc.) should be entered on the article item, though in practice they are sometimes included in the reference as well.

Wikidata item for article: stated in (P248)
Other properties: reference URL (P854), retrieved (P813), quotation (P1683)

Citing a book edit

Wikidata models resources as "works" and "editions" (roughly corresponding to bf:Work and bf:Instance). Citations should link to edition items rather than work items.

Wikidata item for book edition: stated in (P248)
More specific location within the source: page(s) (P304), column (P3903), chapter (P792), section, verse, paragraph, or clause (P958)
Other properties: reference URL (P854), retrieved (P813), quotation (P1683), subject named as (P1810)