Independent and reliable sources. Reliable sources allow editors to verify that claims in an article are accurate. The higher the quality of the source for the statement it backs up, the more likely that statement is to be accurate. Independent sources help editors to write neutrally and to prove that the subject has received note. Wherever possible, editors should aim to use sources that are independent and highly reliable for the subjects they write about.
Theses and dissertations: works created as a requirement for the completion of an advanced postsecondary degree. This page describes some of the considerations in using these types of sources.
Magazine articles: short papers in popular or trade publications.
Newspaper articles or news reports: writing or multimedia that discusses current events or editorial analysis. This page assesses the reliability of news content.
Reports and other grey literature: a broad category that includes most government documents, conference proceedings, and other writings not provided by traditional publishers.
Websites, blogs and other user-generated sources: online content from a variety of authors/publishers. Reliability depends on the editorial control of the website. This page discusses issues with user-generated content.
Many of the best sources are not available online, or are only available under subscription. For example, many books are not available online at all, and subscription to academic databases such as JSTOR can be fairly expensive (although The Wikipedia Library provides access to many subscription databases for free). It doesn't mean that such references are any worse, and it may be worthwhile to make some effort or pay to access them. However, there are often good alternatives that you will be able to access for free or with relatively little effort. That said, never compromise quality for accessibility.
General search engines (e.g. Google or Bing) are effective for finding online sources in particular. You will often need "advanced search" techniques to find the sources faster - thesevideos can help you with the basics.
There is also a lot of free resources - see this compiled list. They may not cover everything but may still be of great help.
Public or research libraries have both books and access to paid research databases, covering a wide variety of subject areas. Find yours, particularly if you are in a large city or close to a university.
If available, bibliographies on a topic outline the main scholarly sources in a subject area and provide a good starting point.
Citation chaining is a great technique to find more information once you found a great source. Simply look up the sources that it cites and sources that cite the article you found. This video describes citation chaining using Google Scholar.
The AI boom has led to the ongoing development of large language model-powered search engines. You can use various LLM tools to look for sources; however, these tools are imperfect, and you must verify that the sources they output actually exist and support the content you are citing them for.
Numerous works are available through shadow libraries, and there are also online tools that circumvent paywalls. Although sometimes they may be the only viable option for you to read the content, Wikipedia does not endorse piracy. Using such tools is illegal in some areas and may be ethically dubious.
The Wikimedia Foundation and Wikipedia volunteers also offer a lot of help.
The Wikipedia Library gives free access to numerous paid databases for active editors with accounts in good standing. Current thresholds are 500 edits on an account that is at least 6 months old, not subject to current sanctions, and which made at least 10 edits in the past month.
The Wikimedia Foundation (WMF) also has a Resource support pilot program, where editors may ask the WMF to purchase resources for you Wikipedia, if other efforts fail.
Volunteers can also help you find your resource. However, it is good practice to try to exhaust all options available to you before seeking other volunteers' help.
The Reference Desk is the Wikipedia equivalent of asking for help from a librarian.
The Resource Exchange is a place where you can ask volunteers to find a specific source for usage in Wikipedia articles.
Some volunteers also declare access to paid/offline resources that they are ready to share. See the list.
If a DOI or other identifier is included, you can click on it to find an online copy of the article. This may or may not be free to access, but will give you a place to start. If the article does not appear free to access, you may still be able to find the article elsewhere, whether online or through a nearby library. Consider the resources in the following points as further guides to accessing such articles.
Install the Unpaywall extension on your browser: you will have a 50% chance of finding the full text in open access, wherever you found it.
Some content will be behind a paywall. However, they may be a chance that you will be able to find an alternative free version. For example, Google Scholar has the "All X versions" or "Related articles" button that may help find your sources.
Citation chaining may sometimes help find similar articles that are free to access.
Using either the DOI, Google Scholar, or the journal's website, find out what databases index the article in full text. You can then see if either your local library or the Wikipedia Library provides access to these databases.
Use WorldCat to see if your local library has a physical version of the journal.
Request the article or the journal through your library's interlibrary loan service, if available.
Reach out to the author(s) of the research paper by email and ask them for a copy.
Google Books will often give access to a few pages or a snippet view.
Internet Archive and Google Books index millions of books, both academic and popular; however, not all will be available in full text.
This video introduces the use of Internet Archive for research. See also WP:IAACCESS on how to get access to additional content.
Several publishers make multiple editions of their books available through Google Books. Sometimes, Google initially returns a link only to the e-book edition, but that edition may include links to alternate hardcover or softcover editions which do have original pagination. Google Books limits previews of copyrighted books to a certain number of pages. It is possible to jump ahead to exhaust that number from a later starting page by editing the browser URL. For example, adding &pg=PA100 will usually jump to page 100. WP:GBOOKS explains how to cite sources found through Google Books.
Installing the Unpaywall extension on your browser helps you find the full text of the articles wherever you found them.
See if other editions are available (although the content or pagination may differ).
WorldCat has millions of books and journal articles, and if you register for a free account, it will show you the closest libraries to you that have the source you are looking for. Some books and articles are available in full-text versions which you can view or borrow online.
Request the book through your library's interlibrary loan service, if available.
If you only need a chapter in a collective work or fragments of a research thesis, reach out to the author(s) of the work by email and ask them for a copy. For full theses, you will often need someone from that university to give them to you. Contact them and see if they have access to that content.
If the source is available in the Wikipedia Library and there is already a Wikipedia article about it, please put {{Wikipedia Library}} on the talk page, so other editors will know that they can access it there.
For subjects that have several names or spellings, it may be desirable to use more than one search. This can be as simple as using several {{find sources}} templates.
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