Somewhere between the last chapter and submission comes the moment when you look at your bibliography one final time. Most people then check the form: ordering, italics, full stop before or after the bracket. The more dangerous errors sit one level deeper — in the question of whether the references are actually right. Does the article exist? Does the DOI lead to the right text? Are the author and year the ones that really appear on the PDF?
This check has become more important in recent years, for three reasons. First: if you research with AI tools, there is a fair chance your bibliography contains entries a language model invented outright — formally immaculate, factually nonexistent. Second: classic typos have always been around — years shifted by one, mangled author names, the wrong edition. Third: DOI junk. Copied DOIs with a truncated suffix, DOIs pointing to the wrong article from the same issue, dead links. Examiners spot-check these today — a DOI that leads nowhere is often the first thread they pull.
This post shows you how to work through your bibliography systematically in one evening. The focus here is the existence and attribution check: does this source exist, and do the details belong together? The second, deeper step — does the source actually say what your text claims — is its own procedure; for that, see the checklist for verifying quotes.
Why exactly these errors are expensive
A wrong italic costs half a mark. A reference that cannot be found raises a different question: did this person ever read the source? From that point on, the examiner reads the rest of your thesis with different eyes — and with a fabricated entry taken over from an AI chat, depending on your examination regulations, what’s on the table is a suspicion of deception, not a formatting slip.
On top of that: this exact class of error slips past the usual toolchain. Zotero formats whatever you feed it — including a fabricated entry, once it has landed in your library. Your university’s plagiarism software compares your text against other texts; whether your sources exist is not its job. If you don’t check the references yourself, nobody checks them before submission.
The checklist: verify your references in one evening
Whether you’d call it checking your citations, verifying your bibliography, or vetting your reference list — it’s the same pass, and it’s built for throughput: sort the whole bibliography by error class first, then work class by class — instead of jumping between Word, browser, and library catalogue for every single entry.
Step 1: Export the bibliography and mark the candidates
Export your bibliography into a separate file or print it — the point is being able to tick entries off. Then honestly mark every source you have never held in full text: taken from a reading list, a footnote, lecture slides, or an AI chat. These entries are your high-risk group. What you read yourself as a PDF and cited from can be misformatted, but is unlikely to be fabricated.
Step 2: Resolve every DOI on doi.org
Take each entry with a DOI and enter it on doi.org. Two things have to hold: the DOI resolves at all, and it lands on the right article — title and authors on the target page must match your entry. The second part is the more important one: a DOI pointing to a different article from the same journal is a common copy-paste error, and a bare “link works” check won’t catch it. A DOI that doesn’t resolve doesn’t yet mean the source is fabricated — but it does mean you now have to verify that entry by hand.
Step 3: Search the DOI-less titles in the databases
For everything without a DOI: search the exact title in quotation marks. Where you look depends on the source type — these are places to check, not a ranking:
- Journal articles: Crossref and OpenAlex cover the large majority of published research; Google Scholar catches much of the rest.
- Books and edited volumes: a library catalogue — in Switzerland swisscovery, in Germany the German National Library catalogue or the Karlsruhe Virtual Catalog.
- Grey literature, reports, university publications: the publishing institution’s website, then the library network.
A hit has to match on all core details: title, authors, year. A similar title with different authors is not a hit — it’s a warning sign, more on that in a moment.
Step 4: Hold author, year, and edition against the PDF
For the sources you have as PDFs: open the first page and compare it with your bibliography entry. Do the names match — all of them, in the right order, spelled correctly? Does the year match, or are you citing the second edition with the year of the first? Especially with textbooks that have gone through several editions, the page numbers shift along with the edition — and then every page reference you give points into the void. This is seconds of legwork per entry, and it catches the most common error class of all: the source exists, but your details about it are off.
Step 5: Cross-check text and bibliography
Finally, the check in both directions: every source cited in the text needs an entry in the bibliography — and every entry in the bibliography has to appear in the text (unless your citation style keeps a separate list of further reading). Orphaned entries come from cutting; missing ones from late insertions. If you work with Zotero and the Word plugin, this rarely happens to you; with hand-typed citations, it’s near certain.
Verifying AI sources: how to spot invented and dead entries
Fabricated references — whether from an AI chat or from an unchecked reading list — follow recurring patterns. If you want to verify AI-suggested sources, these four are what to look for:
- The chimera. Real, well-known authors in the field, a plausible title, a real journal — but this exact combination doesn’t exist. It’s the typical product of a language model, and the reason you verify the exact combination, not the familiarity of the names.
- Too perfect for your topic. The title answers your research question almost word for word. Real papers are rarely that tailor-made.
- A DOI with the wrong target. The link works, but lands on a different article. If you only click instead of comparing, you’ll miss it.
- Unfindable, but cited often. The entry shows up in no database, yet appears several times in your text. The more often you cite a source, the more expensive it gets when it collapses — check your most-cited entries first.
Important for perspective: unfindable does not automatically mean fake. Older German-language titles, conference volumes, and reports are often missing from the big databases. The difference lies in your own history with the source — have you ever seen it yourself? If not, and it stays unfindable: take it out and replace it with something you can verify.
When is a manual pass enough — and when is a tool worth it?
Honest answer: for a seminar paper with fifteen sources, thirteen of which you read yourself, the manual pass above is done in an hour. You don’t need a tool for that.
The math changes as soon as one of three conditions holds: the bibliography has more than 30 to 40 entries; a relevant share comes second-hand (reading lists, AI research); or the deadline is so close that an evening of handwork no longer fits. Then the free Quick Check takes over steps 2 and 3 in one pass: paste in your bibliography, and every entry is matched against Crossref, OpenAlex, swisscovery, and the German National Library — no sign-up, with a findings list of which entries check out and which need a closer look. Whatever remains on the list, you verify by hand — targeted, instead of across the board. How the check works in detail is on the bibliography checker page.
And the boundary, so no false confidence creeps in: this check tells you whether your sources exist and the details belong together. Whether your text attributes something to a source that was never in it is the next level — for that, the full Acurio check compares every cited claim against the full text of the source.
Timing makes the difference
The most common mistake with this check isn’t the how, it’s the when: the day before submission, when a collapsed source can only be deleted, not replaced. Schedule the pass one to two weeks before the deadline. Then an unfindable source is a solvable problem — you find a verifiable replacement, adjust the passage, done. On the last evening, the same source is a hole in your argument.
In short: mark what you never read yourself. Resolve every DOI on doi.org and compare the target. Search the rest in Crossref, OpenAlex, or a library catalogue. Hold author, year, and edition against the PDF. Cross-check text and bibliography. One evening of work — and your bibliography is no longer an open flank, but the part of your thesis that stands up to any spot check.