Wikipedia:How to add sources to Wikidata

This help page is a how-to guide. It explains concepts or processes used by the Wikipedia community. It is not one of Wikipedia's policies or guidelines, and may reflect varying levels of consensus.

When you add information to Wikidata, please cite your sources. Most of the time, it's super easy and requires just four clicks. This page shows how to add sources to Wikidata.

Find the "Statement" you want to add a source for. In the example, which is based on this edit to the Wikidata entry for Varicella vaccine, the statement that needs a ref is the claim that the vaccine is an WHO Model List of Essential Medicines.

Underneath the claim, find "+ add reference". Click that. It will add your source where it currently says "0 references".

The easiest ones to add are plain links to websites or common identifiers (e.g., ISBN, DOI, PMID, etc.) There is a searchable list with common options preloaded. For this example, the webpage https://list.essentialmeds.org/medicines/221 is being added as the source, so click on 'reference URL' in the list:

The 'stated in' option allows you to cite a notable work (e.g., any book that Wikidata has an entry for, which includes all books that Wikipedia has an article about). If you want to cite the WHO Model List of Essential Medicines, or a notable textbook like Harrison's Principles of Internal Medicine, then you can use the 'stated in' option and search for the name of that book. (For a non-notable book, use the ISBN-13 or ISBN-10 options instead.)

When you choose the source type, a new empty box appears next to it. That's where you paste your source (e.g., URL, ISBN, or other id number).

Wikidata sources don't usually add full citation information (e.g., author or publisher names – though this is possible and not very difficult to '+add' page(s) and similar 'properties' immediately under your ref), so you don't usually need to collect or format anything beyond the URL or other key identifier unless you want to.

You can cite multiple sources for the same statement. If you want to add another source for the same statement, in the same edit, then click the '+ add reference' button now and repeat these steps. Alternatively, you can do this as a separate edit.

Click the 'publish' button for the statement.

You're done!