Research guide
Credible Sources for Research: Examples and How to Check Them
Reliable sources are the ones you can trace to original evidence. Here are examples by type, the checks to run before you cite one, and the shortcuts that fail.
What counts as a credible source for research
A credible research source is one a reader can trace: a named author or institution, a date, a method, and references that lead to original evidence. The format matters less than the chain. A government dataset, a peer-reviewed paper, a court record, a company filing and a well-sourced news investigation can all qualify; a summary of a summary, however polished, does not.
The usual school rule of thumb, "prefer .gov, .edu and .org", is a shortcut for this and fails often enough to be dangerous. Judge the chain of evidence, not the suffix.
Examples of credible sources, by type
Use these as starting points, then apply the checks in the next section to the specific page you cite.
- Primary documents: laws and bills (congress.gov, state legislature sites), court opinions (courtlistener.com, supremecourt.gov), company filings (sec.gov EDGAR), patents (patents.google.com).
- Official statistics: census.gov, bls.gov, cdc.gov and data.gov in the United States; ons.gov.uk, eurostat and the World Bank, IMF and OECD data portals elsewhere.
- Peer-reviewed research: PubMed and PubMed Central for medicine, arXiv for preprints in physics, maths and computer science (not yet peer reviewed), Google Scholar to find the published version, and the journal itself for the record of corrections.
- Reference works with editorial control: Encyclopaedia Britannica, the Stanford Encyclopedia of Philosophy, major dictionaries. Wikipedia is a good map to primary sources through its citations, and a poor destination to cite directly.
- Wire services and investigative newsrooms: Reuters and the Associated Press for breaking facts, ProPublica and similar non-profits for document-driven investigations, and the primary documents they publish alongside their stories.
- Fact-checking organisations that show their work: those that publish sources, methods and corrections. Treat any fact check, including Factful, as a guide to the evidence rather than a substitute for reading it.
How to check a source before you cite it
Open the specific page, not the home page. Find the author or institution and the publication date. Locate the original data or document the page relies on and open that too. Confirm that at least one independent source reaches the same conclusion from its own evidence. Note any corrections or updates. If any link in that chain is missing, cite the strongest source you could reach and say what you could not verify.
For a news article, paste the URL into Factful. It extracts each factual claim, retrieves independent reporting and primary documents, and shows which claims are supported, contradicted or unverifiable, with the sources linked.
Sources to avoid, and why
Content farms that rewrite other outlets without new sourcing, anonymous aggregators, pages that cite "studies" without naming them, press releases presented as reporting, and anything that will not tell you who wrote it or when. Social media posts are claims, not sources, until you reach the document behind them.
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Frequently asked questions
What are the most credible sources for research?
Primary documents and official statistics come first (laws, court records, filings, government data), then peer-reviewed research, then reference works with editorial control, then wire services and investigative newsrooms that publish their documents. Within each type, judge the specific page by its author, date, method and references.
Is Wikipedia a credible source?
Use it to find sources, not as one. Its articles cite primary and secondary sources; follow those and cite them instead.
Are .gov and .edu sites always reliable?
Usually for the data they publish, but .edu hosts personal and student pages too, and government sites can present policy positions as fact. Check the author and the method on every page.
How many sources should I use?
Enough that each important claim rests on at least one primary source and one independent confirmation. Two outlets repeating the same press release count as one source.
Can I cite a fact check as a source?
Cite the evidence the fact check links to, and mention the fact check as the path you took. That keeps your work traceable if the fact check is later corrected.