# Checking sources in a Master's thesis before you submit

> How to check a DACH Master's bibliography before submission: second-hand entries first, DOI resolve, catalogue search — a source check, not a citing how-to.

Acurio · 2026-08-27 · Master's thesis, Source checking, Bibliography, Submission

A week before submission Nora sent her supervisor the bibliography. 78 entries, Zotero had formatted everything, the declaration of authorship was already signed. The reply came the same evening: "I don't remember Keller 2019 on organisational learning quite like that — can you send the passage?" Nora searched. The edited volume existed. The chapter she had been citing since the exposé was not in it. The reference had come from a reading list she took out of a chat in her first Master's semester and had not opened since.

That is the typical Master's error. Not a wrong edition number. An entry nobody ever saw in full text, holding up a chapter.

This is not a citing guide. It is how you check the bibliography of a Master's thesis in Germany, Austria or Switzerland before you submit: which entries first, in which order, and what you can still fix in the last week.

**In short:** mark everything you never held in full text. Resolve every DOI at doi.org, search the rest as an exact title in catalogues and databases, reconcile text and list. Existence runs across the whole bibliography; content you check on the references that carry the thesis. The fastest existence pass is the [bibliography checker](https://acurio.ch/en/bibliography-checker).

## Why a Master's thesis needs a different check

You [check a term paper in half an hour](https://acurio.ch/en/blog/term-paper-source-check) because the list is short and most entries are from the last six weeks. A bachelor's thesis often has [25–50 sources](https://acurio.ch/en/blog/how-many-sources-for-a-bachelor-thesis), and you fetched many of them yourself. A Master's thesis sits higher — typically 50–100 sources — and it grows over months.

That changes the check.

| Where the entry came from | Why it is risky |
|---|---|
| Supervisor reading list | You take the title without opening the PDF |
| Bibliography of your own bachelor's thesis | Details are old; editions and DOIs may have moved |
| Footnote in someone else's text | The chapter in the edited volume often does not exist as cited |
| AI chat or AI research | Formally clean, often invented or matched to the wrong work |

You do not need to re-read 80 PDFs in the last week. You need the entries you never saw yourself — and the few references the thesis actually stands on.

Existence is one pass over the whole list: [free check, no signup](https://app.acurio.ch/quick-check?lang=en&utm_source=seo&utm_medium=landing&utm_campaign=masterarbeit_w35).

## What you can still check in the last week — and what you cannot

Two days before submission you can delete a fabricated source. You cannot rebuild the chapter that rested on it.

So you split the check:

1. **Existence and attribution** for the whole bibliography. Does the title exist? Does the DOI land on the right work? Do author and year match the PDF?
2. **Content** only for the references that carry your research question, the central claim and the conclusion.

The first part is what plagiarism software never does. The second is what a supervisor samples. Most people confuse both with formatting — italics, the full stop before the bracket. Formatting is your reference manager's job. More in the [Zotero workflow tips](https://acurio.ch/en/blog/zotero-workflow-tips) and in [creating a bibliography in Word](https://acurio.ch/en/blog/create-a-bibliography-in-word).

The evening pass for existence and attribution is the same procedure as in [how to check your citations](https://acurio.ch/en/blog/how-to-check-your-citations). The Master's version is: sort by origin first, then run the list, then read only the supporting passages that carry the argument.

## The pass: origin, existence, supporting references

### Step 1: Mark the origin

Go through the bibliography once and tag every entry:

- **R** = read. You had the PDF or the book open.
- **B** = taken over from your bachelor's thesis.
- **S** = second-hand. Supervisor list, footnote, slide, chat.

**B** and **S** are your check list. A recycled bachelor's entry is not automatically wrong, but it is unverified for *this* thesis.

### Step 2: Resolve every DOI

For every entry with a DOI, paste it into [doi.org](https://www.doi.org). Three possible outcomes:

- Lands on the right work → existence is done.
- Lands on a *different* article in the same journal → copy error, fix it.
- Does not resolve → warning. Go to step 3.

The target has to match the entry, not just "the link works". More under [DOI, ISBN and ISSN](https://acurio.ch/en/blog/doi-isbn-issn-in-citations).

### Step 3: Search titles without a DOI in catalogues

Books, chapters in edited volumes, university publications and older German-language titles often have no DOI. Search the **exact title in quotation marks**:

1. [Crossref](https://search.crossref.org) and [OpenAlex](https://openalex.org) for journal articles
2. Your university library catalogue
3. [swisscovery](https://swisscovery.slsp.ch), the [German National Library catalogue](https://portal.dnb.de) or the Karlsruhe Virtual Catalog
4. For edited volumes: the title of the *volume* and of the *chapter*, separately

A volume that exists and a chapter that is not in it: exactly Nora's case. That is the most common fabricated entry that looks almost real.

### Step 4: Reconcile text and list

Two directions:

- Does every source cited in the text appear in the bibliography?
- Does the bibliography contain a source that appears nowhere in the text?

Orphaned entries come from cutting. Missing ones appear when you insert a passage late and never add the entry in Zotero. Both show up in the first glance at the list.

### Step 5: Read the supporting passages that carry the thesis

Not the whole list. The places a supervisor looks up:

- the reference for the research question
- the reference for the central claim
- the most recent source
- every title that fits the question unusually well

Open the page. Is there a sentence that supports your wording — not merely the same topic? If not, you have a content error. That one looks deliberate, even when it came from memory. The distinction is in [plagiarism vs. misquotation](https://acurio.ch/en/blog/plagiarism-vs-miscitation). For the deeper quote-against-full-text pass, [checking quotes in a bachelor's thesis](https://acurio.ch/en/blog/checking-quotes-in-a-bachelor-thesis) is the checklist — same method, different scale.

> **Fast start:** paste the bibliography and see within a few seconds which entries can be verified in catalogues and databases. [Free check, no signup →](https://app.acurio.ch/quick-check?lang=en&utm_source=seo&utm_medium=landing&utm_campaign=masterarbeit_w35)

## Three Master's traps a term paper does not have

**The supervisor list.** A title your supervisor named herself feels verified. It is not. You copied it. If it does not exist, or the edition is wrong, she is the first person who will notice.

**The recycled bachelor's bibliography.** Details that were right two years ago are not automatically still right. Later editions move page numbers. DOIs get added or corrected. An entry you never opened then is still unverified.

**AI research over months.** In a Master's that accumulates, because you add to lists over a year and forget where an entry came from. An entry from a chat is unverified, even when it looks formally clean. How to spot invented entries is in [ChatGPT and hallucinated sources](https://acurio.ch/en/blog/chatgpt-hallucinated-sources).

What a signed declaration of authorship means in practice is covered under [the declaration of authorship and its consequences](https://acurio.ch/en/blog/false-declaration-of-authorship-consequences).

## What plagiarism software does not check on a Master's thesis

| | Plagiarism scan | Source check |
|---|---|---|
| Text copied from elsewhere | finds it | not its job |
| Source does not exist | no | yes |
| Source says something else | no | yes, if you read the passage |
| DOI points at the wrong work | no | yes |

Turnitin, PlagScan and Ouriginal compare text with text. A fabricated source has no foreign text. It passes, with a clean report. That is not a bug. These are two different checks.

## When Quick Check is the door

For a seminar paper with a short list you mostly read yourself, the manual pass is enough. For a Master's thesis with 50–100 entries and a real share of second-hand items, the bottleneck is not the close reading — it is finding *which* entries you need to read closely.

The free [Quick Check](https://app.acurio.ch/quick-check?lang=en&utm_source=seo&utm_medium=landing&utm_campaign=masterarbeit_w35) takes existence and catalogue matching in one pass: paste the bibliography, no signup, findings list. Whatever remains, you check by hand. How that looks on the product page is on the [bibliography checker](https://acurio.ch/en/bibliography-checker).

That tells you whether the sources **exist and the details belong together**. Whether your sentence is in the source stays your reading of the supporting passages.

## What this check is not

- **Not a citing guide.** Style, footnote or parenthesis, APA or Harvard — that was decided earlier, not in the last week.
- **Not a bachelor's quote check.** Matching every claim against the full text is a separate, longer pass.
- **Not a BHS diploma thesis.** There the bibliography is shared and the citation schema is set by the ministry — a different check, and a different audience.
- **Not a doctoral dissertation.** That range starts at 150+ sources and is a different procedure.

If you are handing in a shorter paper at the same time, the matching check is [checking sources in a seminar paper](https://acurio.ch/en/blog/checking-sources-in-a-seminar-paper) — ten minutes, a different bar.

## What to take away

1. **Check origin, not format.** Start with the entries you never held in full text.
2. **Existence for all, content for the thesis.** Supervisors look up the supporting references, not the punctuation.
3. **DOI first, then the catalogue.** Search volume and chapter separately.
4. **Plagiarism software does not cover this.** It checks overlap, not existence.
5. **Early enough that a replacement still fits.** A collapsed source in the last week is a hole, not a correction.

A Master's thesis rarely fails for lack of literature. It becomes uncomfortable when the bibliography contains something you never saw and that the supervisor looks up first. That is one pass, not a second semester.

**Start with the fastest step:** paste the bibliography into the Quick Check and see which entries can be verified. Free, no signup.

[Check your bibliography now →](https://app.acurio.ch/quick-check?lang=en&utm_source=seo&utm_medium=landing&utm_campaign=masterarbeit_w35)


## Frequently asked questions

### How do I check the bibliography of a Master's thesis before submission?

First mark every entry you never held in full text. Then resolve every DOI at doi.org and search the rest as an exact title in Crossref, OpenAlex and your library catalogue. Finally reconcile the text against the list. Run the existence check across the whole bibliography; read the full text only for the references that carry your thesis.

### Do I really have to check every source in a Master's thesis?

Every source you did not read yourself. What you quoted from the PDF is done for existence. What arrived from a supervisor reading list, from your bachelor's bibliography, from a footnote or from an AI chat is not. Those are the entries you check first.

### Will Turnitin or PlagScan catch sources that do not exist?

No. Plagiarism scanners compare your text with other texts. They check neither whether a cited source is real nor whether it says what you claim. A fabricated reference passes, because there is no foreign text for it to match.

### How many sources does a Master's thesis usually have?

A useful range is 50–100 sources. That is not an official minimum — it is the band most DACH Master's theses land in. For how the number shifts by field and method, see «How many sources does a bachelor's thesis need?» — that post also states the Master's and doctoral ranges.

### What if I cannot find a source anywhere?

Not findable does not automatically mean fabricated. Grey literature, university publications and older German-language titles are often missing from the big databases. Check your university catalogue first, then swisscovery, the German National Library catalogue or the Karlsruhe Virtual Catalog. If nothing turns up and you never saw the source yourself, cut it and replace it.

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Source: https://acurio.ch/en/blog/checking-sources-in-a-masters-thesis