Is That Citation Real? Check It, Practice Spotting Problems, and Learn to Verify Sources Yourself
by
Professor Stephen T. Abedon
Steve Abedon, Ph.D., has taught well over 100 individual classes and ~10 individual courses (including introductory biology, microbiology, physiology, biochemistry, etc.) over his
30+ years as a college professor. He has over 150 publications, including multiple monographs, and is ranked
in the top 1 or 2 percent among researchers of all disciplines worldwide.
His research focuses on bacteriophage biology and phage therapy.
What is this?
A tool for checking whether citations are real. Paste a reference list in the Check tab, and each
reference is looked up in the Crossref and OpenAlex scholarly databases and compared field by field with the closest
record found: title, first author, year, journal, volume, and first page. The DOI of each matched work can be copied
with one click. The Practice tab has citations
to sort before running them through the checker, and the By Hand tab explains how to check a reference
without any tool at all.
🔒 Privacy: the references you check are sent from your browser to the public Crossref, OpenAlex, and
DataCite databases to be looked up. Nothing is stored, and nothing is sent anywhere else.
Paste references below, one per line or separated by blank lines, and select Check references.
Each reference is looked up in the Crossref and OpenAlex databases, and any DOI it contains is checked to see which paper
it actually belongs to. When a reference matches a database record, that record's DOI can be copied, so references
missing a DOI, or carrying the wrong one, can be completed. The list below holds examples, so you can see every kind
of result before pasting your own.
About the examples. The list mixes real and problem citations from the bacteriophage literature:
A real article, no DOI given.
A real article with its correct DOI.
A real article, no DOI given.
The same real article as #1, with its year, journal, volume, and pages changed.
The real article from #2, given the DOI of a different paper.
An invented article attributed to a real author.
A real book, of the kind often missing from article databases.
DOIs found:
🧪 Practice: Which Citations Are Real?
Below are eight citations to classic and recent biology papers. Some are exactly right, and some are not.
Decide what each one is before using the checker. The methods in the By Hand
tab are all you need: open the DOI, search the title, and compare what you find with what the citation says.
Sorting first and checking second is the point. A tool that answers for you teaches you to trust the
tool, while sorting first teaches you what a problem citation looks like.
Categories
Real and correct: the work exists, and the citation describes it accurately.
Real, details wrong: the work exists, but the year, journal, volume, or pages are off.
Real, wrong DOI: the work exists, but the DOI given belongs to a different work.
Invented: no such work exists, even if the authors and journal do.
Real, hard to find: the work exists but is missing from the article databases, as many books are.
🔎 Checking a Reference by Hand
Every check the tool makes can be done by hand in a few minutes, and doing it by hand catches things no
tool can. Work through these steps in order, stopping once the reference is confirmed or clearly fails.
Start with the DOI, if there is one. A DOI (digital object identifier) is a permanent address for
a published work. Type https://doi.org/ followed by the DOI into a browser. The page that opens should be
the work cited, with the same title and authors. A DOI that goes nowhere, or that opens a different paper, is a red flag.
The first part of a DOI often hints at the publisher or journal: 10.1073/pnas belongs to the
Proceedings of the National Academy of Sciences, for example, so a citation to some other journal carrying that DOI deserves a closer look.
Search the exact title. Put the title in quotation marks in
Google Scholar, or search it in
PubMed for biomedical work. Real journal
articles almost always turn up. If nothing does, try a few distinctive words from the title without the quotation marks,
since citations are sometimes copied with small changes to the wording.
Compare the details. Once you find the work, check the citation against it: author names and order,
year, journal, volume, and pages. A mismatch can be an innocent typo, but several mismatches together suggest the
citation was assembled from memory, copied carelessly, or invented around a real title.
Check that the journal and volume make sense. Does the journal exist? Was it publishing in that
year? Does that volume number belong to that year? The journal's own website lists its back issues.
Check the authors. Do the named authors work in this field? Their publication lists on Google
Scholar, ORCID, or PubMed show what they have actually written.
Fabricated citations often attach a plausible title to real people who never wrote it.
For books and chapters, use a library catalog. Books are thinly covered by article databases. Search
WorldCat or your own library's catalog instead.
Read the source. A citation can point to a real paper that does not say what the citation claims.
Only reading the cited passage catches this, and no reference checker can do it for you.
Ask a librarian. Reference librarians track down obscure, old, and foreign-language sources every
day, and they are usually glad to help.
Signs that deserve a second look
A title that matches the argument being made a little too perfectly.
Methods or ideas that did not exist in the year given, such as CRISPR gene editing in a paper from the 1980s.
A DOI whose prefix belongs to a different publisher or journal than the one named.
Page numbers that are implausible for the journal, or an article number in a journal that uses page numbers.
A list in which no citation includes a DOI or link, for recent work that would normally have one.
A reference you were given by an AI tool that did not show you where it found the reference.
🤖 Why Fake Citations Happen
How AI tools produce them
Chatbots built on large language models generate text by predicting what plausibly comes next. A citation has a
very regular pattern: author names, a year, a title, a journal, and a set of numbers. A language model can produce text
with that pattern fluently, drawing on the names, topics, and journals it has seen, without ever looking up whether the
combination exists. Unless an AI tool actually searches for a source and links you to it, a citation it gives you is
expected to be a reconstruction rather than a record, and it can be partly or entirely made up while looking completely ordinary.
How often this happens has been measured. Walters and Wilder (2023) asked two versions of ChatGPT to write short
literature reviews and then checked the 636 citations produced. With GPT-3.5, 55% of the citations were to works that
do not exist, compared with 18% for GPT-4. Among the citations to real works, 43% (GPT-3.5) and 24% (GPT-4) contained
substantive errors, such as a wrong year, journal, or page range. Newer tools, especially ones that search the web,
are expected to do better, but none should be assumed to be error-free.
Why it matters
A citation is a promise that the source exists and supports what is being said, so that a reader can go and check.
A fabricated citation breaks that promise even when the statement it supports happens to be true. The consequences can
be serious. In 2023, lawyers in the case Mata v. Avianca
filed a brief citing court decisions that did not exist. The decisions had been generated by ChatGPT, and the court fined the lawyers.
People make citation errors too
Not every bad citation comes from AI, and not every bad citation is dishonest. People copy references from other
reference lists without reading the source, mistype volume numbers, and misremember years. Those are errors, and they are
worth fixing, but they are different from citing something that does not exist. When the checker flags a reference,
the right first question is what went wrong, not who to blame.
What this means for you
List only sources you have actually seen. A reference list is a claim that you have looked at each work in it.
AI tools can be a reasonable place to start looking for sources, but treat every reference one gives you as
unconfirmed until you have found the work itself.
When you copy a citation from another paper, check it against the original. Errors spread by copying.
Assume someone will check. Instructors, reviewers, editors, and librarians increasingly do, often with tools much like this one.
Reference
Walters WH, Wilder EI. 2023. Fabrication and errors in the bibliographic citations generated by ChatGPT.
Scientific Reports 13:14045. doi:10.1038/s41598-023-41032-5
📖 How the Checker Works
Steps
The pasted list is split into individual references, and any DOI in each reference is pulled out.
A cited DOI is looked up directly, first in Crossref,
then in OpenAlex, then in
DataCite. Crossref registers most journal DOIs,
and DataCite registers DOIs for datasets and repositories such as Zenodo.
The full reference is sent to Crossref's bibliographic search, which returns the closest matching records. If no
record's title matches, a probable title is pulled from the reference and searched in OpenAlex.
Each candidate record is compared with the reference. The title check counts how many of the record's title words
appear, in order, in the reference. The first author's surname, the year, the journal (in full or abbreviated), the
volume, and the first page are each checked for presence in the reference.
What each result means
Verified
A record's title matches, and its first author, year, volume, and first page are consistent with the reference.
Details disagree
The title matches a real record, but other details do not. A real title attached to the wrong year, journal, or authors is a common signature of fabricated citations, and also of ordinary copying errors.
Possible match
A record's title partly matches. Check by hand.
DOI points elsewhere
The cited DOI exists but belongs to a work with a different title.
DOI not found
The cited DOI was not found in Crossref, OpenAlex, or DataCite.
Not found
No record with a matching title was found. This is a reason to look further, not proof that the work does not exist.
Limits
Books, chapters, theses, conference abstracts, reports, and much of the older and non-English literature are thinly
covered by these databases, so real works of these kinds may be reported as not found.
A real paper cited for a claim it does not make passes every check here. Only reading the source catches that.
Matching is approximate. Unusual citation styles, typos, and errors in the databases themselves can all produce
flags for references that are fine.
Every flag is expected to need a human look before any conclusion is drawn about a reference, or about the person who cited it.
The Check tab needs an internet connection. The other tabs work offline.
Finding DOIs
Any reference matched to a database record gets a Copy DOI button: references marked Verified or
Details disagree, and references whose cited DOI points elsewhere but whose title matched a record separately. For a
Possible match, the button is labeled as unconfirmed, because the record may be a different work. Above the results,
Copy DOIs copies one line per reference, in order, and Copy references with DOIs added
copies the list with each confirmed DOI attached, replacing any wrong DOI. Adding a DOI does not correct a reference's
other details, so references marked Details disagree still need fixing by hand.
A suite of free, browser-based
phage biology (🔬) and
phage therapy (💊)
calculators by Stephen T. Abedon. All open in a new browser tab.
Loaded live from phage.org;
hidden when the app is used offline.