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Short answer
Peer-reviewed references are sources that experts in the same field evaluated before publication, usually articles in journals that state their review process. Directories label peer review per journal, not per item, so confirm the journal’s policy and the type of item you are citing: editorials, news and preprints held in the same database may not have been reviewed.
Definition and scope: what counts as a peer-reviewed source?
Kelly, Sadeghieh and Adeli quote this definition: peer review is “a process of subjecting an author’s scholarly work, research or ideas to the scrutiny of others who are experts in the same field.” Ulrichsweb, the serials directory, treats “refereed” and “peer-reviewed” as the same thing, covering several models such as double-blind and expert review.
A peer-reviewed reference is therefore an item that went through that evaluation at the journal that published it. The label describes a process, not whether the findings are right; the peer review guide explains the process.
How to check that a reference is peer reviewed: five steps
- Identify the item type. Is it a research article, or an editorial, news item, book review or preprint? The checks below describe the journal, so they cannot tell you how a non-research item was handled.
- Find the journal’s own policy page. ProQuest’s selection policy expects a journal website to give basic information about the publisher, editors, review process and scope. DOAJ requires the type and details of the peer review process to be stated clearly on the website. MEDLINE’s scientific quality review asks, among other things, whether the process is explicit, including the type of review and the number of reviewers typically assigned.
- Look the title up in a serials directory. In Ulrichsweb, a title shows a “Refereed” icon (an image of a referee’s jersey) only once its peer-review information has been confirmed. “Refereed” is also a search limiter.
- Check the selection criteria of the index that lists it. MEDLINE’s journal selection, DOAJ’s criteria and ProQuest’s title-selection policy all consider the journal’s editorial policies. Inclusion reflects an assessment of the journal, not of each item.
- Treat the result as one signal. Peer review has known limits (see below), so read the study too.
Where each lookup stops: journal level versus item level
| Where you look | What it can confirm | What it does not confirm |
|---|---|---|
| Ulrichsweb “Refereed” flag | The title is refereed, based on information from publishers and journal websites. | The designation “is assigned at the title level rather than at the article level or platform level”, so it says nothing about an individual item. |
| ProQuest databases | Scholarly journals are selected against a published policy that takes peer review descriptions into account. | Many databases also hold trade journals, magazines, newspapers, blogs, preprints, working papers and conference proceedings that do not claim peer-reviewed status. |
| PubMed and MEDLINE | Journals are chosen after a scientific quality review that looks at whether the peer review process is explicit. | NLM states that the majority of MEDLINE publications are scholarly journals, but a small number of newspapers, magazines and newsletters have historically been included. See what MEDLINE selection does and does not tell you. |
| DOAJ (open access journals) | Published criteria say all articles must pass through peer review, with at least two independent reviewers per article (arts and humanities journals may use two editors instead). See the DOAJ entry. | The criteria are set at journal level and apply to open access journals only. |
Types and related concepts
| Term | What it means |
|---|---|
| Academic / scholarly | In Ulrichsweb, a serial type describing the primary audience of a publication. A publication can have this designation without “refereed”, and the reverse. |
| Open, single-blind, double-blind review | Kelly et al.: in open review both identities are known, in single-blind the reviewer’s identity is hidden, in double-blind both are hidden. Single-blind is by far the most common. See the comparison of the three models. |
| Preprint | ProQuest lists preprints among the content types that do not claim a peer-reviewed status. See preprints versus peer-reviewed articles. |
Where it matters in research practice
A database can be a first filter, but the MEDLINE and ProQuest policies above are journal-level and neither promises that every item is reviewed. Nor is review a guarantee of correctness. In a BMJ experiment cited by Kelly et al., a paper with eight deliberate errors went to 420 potential reviewers; 221 (53%) responded, on average they found two errors, none found more than five, and 35 (16%) found none.
Common misunderstandings
- “Every result under a peer-reviewed filter was reviewed.” The flags above sit at journal level, so an editorial or news item inside a reviewed journal can still appear.
- “If a database indexes it, it is peer reviewed.” MEDLINE and ProQuest both state that they include some content that is not a scholarly journal or does not claim peer-reviewed status.
- “Peer reviewed means true.” A 2002 JAMA study quoted by Kelly et al. concluded that editorial peer review “is largely untested and its effects are uncertain.”
Frequently asked questions
What is peer review in research?
Scrutiny of a scholarly work by experts in the same field before publication. Kelly et al. describe two purposes: filtering for validity, significance and originality, and improving manuscripts that are suitable for publication.
Why is peer review important?
Journals use it to screen for quality and to give authors suggestions and corrections before publication. For a reader it is one signal, not proof of correctness.
What counts as a peer-reviewed source?
An item published in a journal whose stated process includes evaluation by experts. Magazines, newspapers and blogs held alongside journals in databases do not count.
How do you know if your references are peer-reviewed?
Confirm the item type, read the journal’s policy page, check a directory such as Ulrichsweb, check the index’s selection criteria, and read the study critically.
Where can I find peer-reviewed references?
Start with sources whose selection rules you can read: PubMed and MEDLINE for biomedicine, DOAJ for open access journals, Ulrichsweb to check a title, and databases such as ProQuest. Results can include other content types, so check each one.
What are examples of peer-reviewed sources?
A research article in a journal that states its review process on its website and is flagged as refereed in a directory is the clearest case. Non-examples include the content types ProQuest lists as not claiming peer-reviewed status, such as trade journals, magazines, newspapers, blogs and preprints.
Is APA a peer-reviewed source?
No. APA Style is a convention for formatting papers and citations, and a reference formatted in APA tells you nothing about whether the work was reviewed. The American Psychological Association also publishes journals; each journal’s own policy settles whether its items are peer reviewed. See the APA Publication Manual guide for the style.
Who actually does the peer review?
Experts with competence in the subject areas the journal covers. Editors first screen manuscripts for fit, then send suitable ones to reviewers. A reviewer does about eight reviews per year on average, per a Publishing Research Consortium study cited by Kelly et al.
Are reviewers paid for their work?
Typically not. Kelly et al. state that referees are typically not paid, and list reasons reviewers give, such as academic duty and keeping up to date with their field.
How to do a peer review of a research paper?
Per Kelly et al., a reviewer first checks that the subject suits the journal, then asks whether the research question is important and original, then works through the paper from title and abstract to methods, results, discussion, conclusions and references. The peer review guide has the full walkthrough.
What are the downsides of peer review?
Kelly et al. summarise the criticisms: it is slow, open to perceived bias, unpaid, and there is little evidence that it works as an effective screen. Some conferences accept papers without thorough review, and review is often criticised for missing plagiarism.
Sources
- Kelly J, Sadeghieh T, Adeli K. “Peer Review in Scientific Publications: Benefits, Critiques, and a Survival Guide.” EJIFCC 2014;25(3):227-243. PMC4975196 (as of 2026-11-07).
- Ex Libris Knowledge Center. “Ulrichsweb: Peer-Reviewed/Refereed Journals and Academic/Scholarly Journals.” Ex Libris Knowledge Center (as of 2026-11-07).
- ProQuest. “Editorial and Title Selection Policy: Scholarly Journals.” ProQuest policy PDF (as of 2026-11-07).
- National Library of Medicine. About MEDLINE (last reviewed 8 September 2025) and Journal Selection for MEDLINE (as of 2026-11-07).
- Directory of Open Access Journals. Guide to applying (as of 2026-11-07).
