Help:Sources

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The majority of statements on Wikidata should be verifiable insofar as they are supported by referenceable sources of information such as a book, scientific publication, or newspaper article. In Wikidata, references are used to point to specific sources that back up the data provided in a statement.

References, like statements, also consist of at least one property-value pair (for a reference, the value is the source). Typically the property used for sources is one of two options: stated in (P248) (referring to publications and media) and reference URL (P854) (used for websites and online databases).

This guideline explains when it is necessary to add a source to a statement in Wikidata. It also explains the steps to be followed in order to add a source.

Language independent general principles[edit]

When to source a statement[edit]

Wikidata is a collection of sourced data, which means that most statements should indicate where the data comes from.

In some cases sources are not required:

  1. When a value is common knowledge, and it has not been disputed. For example, it is common knowledge that Earth (Q2) is an instance of (P31) a terrestrial planet (Q128207)
  2. When the item has a statement that refers to an external source of information (such as a database or authority control file) which allows easy verification of the statement. For example, a statement about Harry Potter and the Philosopher's Stone (Q43361)'s GND identifier (P227) (an authority file maintained by the German National Library) does not need a source (the value, 4615979-4, is a direct link to the appropriate page on the German National Library's website)
  3. When the item itself is a source for a statement. For example, for The Hunger Games book series, it's possible to say that author (P50) is the Suzanne Collins (Q228624) without needing to then include The Hunger Games trilogy (Q11679) as a reference for this statement.

For more information, see Help:Sources/Items not needing sources.

Adding a source to a statement[edit]

example of a sourced statement

There are three basic steps to follow when adding a source regardless of the type of source being added.

  1. Check if an item for the source already exists in Wikidata using the Item by Title search
  2. Add the source as an item if: i) it's not in Wikidata already and ii) it is not a webpage
  3. Add a reference to your statement and point to the source item. For source items in Wikidata use the property stated in (P248); for sources that exist online outside of Wikdiata, use reference URL (P854)
  4. Add the source and all necessary qualifiers

More information on searching for and creating items can be found at Help:Editing.

Different types of sources[edit]

References should point to reliable sources of information such as university-level textbooks or reference books, academic journals, and newspapers. For more information on identifying reliable sources, please see the Wikipedia guideline on the topic.

Please note that while pages on Wikipedia (and other Wikimedia sites) should and can be added as sitelinks, they are not appropriate as sources for Wikidata statements. As per the Wikipedia policy on verifiability, the content of articles in Wikipedia must be verifiable; it should be supported by sources also (in the form of citations). However, just because something is stated on a Wikipedia page, does not mean that it is acceptable to consider the Wikipedia page itself as a source; it's much better to locate the actual citation and use that instead. For this reason, statements that are only supported by "imported from (P143)" are not considered sourced statements. If you encounter one of these statements, please remove "imported from" and add a more reliable source.

This list is not complete and types of sources in addition to the ones found on this page may be reliable; if you would like to add a new section with instructions on how to add such sources, please do so.

Books[edit]

In Wikidata, books are treated according to the Functional Requirements for Bibliographic Records (FRBR) model, a commonly used conceptual framework in library science.

Without going into too much detail, the FRBR model allows us to make a distinction between creative works, and their different editions or translations; in Wikidata, these are known as work items and edition items respectively. For example, we can say that Hamlet and the Bible are work items, while Hamlet, Prince of Denmark (1985 edition by Philip Edwards) and the the King James Version are edition items.

When sourcing statements, you should only ever use the edition item of a book. In some cases, it will be necessary to first add the work item to Wikidata in order to create an edition item. You can do so by following the steps below:

  1. Check if the work item already exists in Wikidata. If an item is found, proceed to step 4. If the item is not found, create a new one for it and go to step 2.
  2. Add at least the following statements to the work item:
  3. Add any additional properties to the work item that may seem necessary, for example:
  4. Check if the edition item of your work item exists in Wikidata. If an item is found, proceed to step 8. If the item is not found, create a new item for the edition and go to step 5. Make sure to label the edition item in a way that can be differentiated from the work item
  5. Label the new edition item in a way that can be differentiated from the work item by adding the edition number with the title
  6. Add at least the following statements to the edition item:
  7. Add any additional properties to the edition item that may seem necessary, for example:
  8. Return to the item page you were adding a reference to source your statement with stated in (P248) and link it to the edition item
  9. Add any additional properties to the reference section which can help when verifying the value of the statement:

Example:

Work item: CRC Handbook of Chemistry and Physics (Q904273), edition item: CRC Handbook of Chemistry and Physics (92nd edition) (Q11927173)
Used to source statement: CAS registry number (P231) of ethanol (Q153)
Reference: stated in (P248)CRC Handbook of Chemistry and Physics (92nd edition) (Q11927173)

Scientific, newspaper or magazine article[edit]

Publication articles requite that both the publication and the article be added as items to Wikidata (if they haven't already been).

  1. Check if the publication item already exists in Wikidata. If an item is found, proceed to the next step. If the item is not found, create a new one for it.
  2. Ensure that at least the following statement is added to the publication item:
  3. Now create another new item, this time for the article
  4. Ensure that at least the following statement is added to the article item:
  5. Return to the item page you were adding a reference to
  6. Source your statement with stated in (P248) and link it to the article item
  7. If needed, return to the publication item and add additional properties:
  8. If needed, return to the article item and add additional properties:

Example:

Journal item: Geological Society Special Publication (Q15817216), article item: The age of the Earth in the twentieth century: a problem (mostly) solved (Q15545344)
Used to source statement: start date (P580) of the Earth (Q2)
Reference: stated in (P248)The age of the Earth in the twentieth century: a problem (mostly) solved (Q15545344)

Reports, policy, legislation and technical documentation[edit]

  1. Check if the article item exists in Wikidata. If an item is found, proceed to the next step. If the item is not found, create a new one for it.
  2. Ensure that at least the following statement is added to the publication item:
  3. Return to the item page you were adding a reference to
  4. Source your statement with stated in (P248) and link it to the article item
  5. If needed, return to the article item and add additional properties:

Example:

Legislation item: Civil Marriage Act (Q3258612)
Used to source statement: start date (P580) of Same-sex marriage in Canada (Q17447)
Reference: stated in (P248)Civil Marriage Act (Q3258612)

Web page[edit]

  1. Check if the web page item exists in Wikidata. If an item is found, source your statement with stated in (P248) and link it to the web page item. If an item is not found, do not create one for it; instead proceed to step #2
  2. Source your statement with reference URL (P854) and link it to the URL of the webpage
  3. Add the following qualifiers to your reference so the source can be tracked down if the URL changes:
  4. If needed, add additional qualifiers:
    • author (P50) and publisher (P123). Please note if the web page belongs to a major web site that already has an item in Wikidata, you should use publisher.

Examples:

Web page item: United States Population Clock (Q3398022)
Used to source statement: population (P1082) of United States of America (Q30)
Reference: stated in (P248)United States Population Clock (Q3398022)
Non-web page item
Used to source statement: date of birth (P569) of Giambattista Bodoni (Q220768)
Reference: reference URL (P854)http://www.treccani.it/enciclopedia/giambattista-bodoni_%28Dizionario-Biografico%29/

Databases[edit]

Please note: this approach only applies to databases that already have a corresponding property defined in Wikidata. The property is often an identifier unique to the database such as the PubMed ID (P698) for PubMed or the IMDb identifier (P345) for the International Movie Database. Consult the list of properties for authority control IDs to determine whether the database property has beed added to Wikidata. You can also use the advanced options of Special:Search to search for the database and/or its identifiers in the Property namespace. If no such property exists for the database, treat the database as a webpage (see above).

  1. Search for the database item in Wikidata. If an item is found, proceed to the next step. If the item is not found, create a new one for it.
  2. Ensure that at least the following statement is added to the database item:
  3. Return to the item page you were adding a reference to
  4. Source your statement with stated in (P248) and link it to the database item
  5. Add the following qualifiers to your reference in order to indicate the specific register of the database.
    • database property → database property ID (the unique identifier for the data as per the database)
    • date of publication (P577) → the publication date for the data
    • if no publication date is provided: date retrieved (P813) → the date when the data was taken from the database

Example:

Database item: PubChem (Q278487), database property: PubChem ID (CID) (P662)
Used to source statement: InChI (P234) of ethanol (Q153)
Reference: stated in (P248)PubChem (Q278487)

Media & Entertainment (TV/radio/music/video)[edit]

  1. Check if the media item exists in Wikidata. If an item is found, proceed to the next step. If the item is not found, create a new one for it.
  2. Source your statement with stated in (P248) and link it to the media item
  3. If needed, return to the article item and add additional properties:

Example:

Documentary item: Man on Wire (Q1417721)
Used to source statement: occupation (P106) of Philippe Petit (Q705289)
Reference: stated in (P248)Man on Wire (Q1417721)

Guidelines for sources in English[edit]

  1. There are plans to add a monolingual data type property to Wikidata in the future that will eliminate the need to add "original language" titles and other information to items. Until the data type is added, please always add the original language title under title (P357) in order to allow an easy conversion.

See also[edit]

For related Help pages, see:

For additional information and guidance, see:

  • Wikidata:Project chat, for discussing all and any aspects of Wikidata
  • Wikidata:Glossary, the glossary of terms used in this and other Help pages
  • Help:FAQ, frequently asked questions asked and answered by the Wikidata community
  • Help:Contents, the Help portal featuring all the documentation available for Wikidata