One of the most common last-minute questions in a thesis is: “My most important source is in another language — can I just translate the quotation?” The answer is rarely as clean as students hope. It depends on your source language, your target language, your discipline, your citation style, and your department’s own rules. This guide sorts through the rules and shows, with concrete examples, how to weave foreign-language sources cleanly into your bachelor’s or master’s thesis.
The core principle: original before translation
Academic citation is a chain of evidence. Anyone who cites a claim must be able to point to it in the original — not in a version someone has reworked. In practice:
- The original source always goes in the bibliography — never a translation you produced yourself.
- The original quotation is the reference. If you translate, the translation is an addition, not a replacement.
- You mark your translations. Who translated and how must be visible to the reader.
Everything beyond that is convention, and conventions vary by language and discipline.
The Quick Check tells you whether the original sources exist and the reference details are correct. Translation fidelity is what the full analysis checks against the source text, not this check.
English sources in an English-language thesis — the trivial case
If both your source and your thesis are in English, no translation question arises. Cite as you would any English source under your chosen style (APA, Harvard, Chicago). The complications only begin when source language and thesis language diverge.
English sources in a non-English thesis
At most Continental European universities English is treated as a working scientific language. The overwhelming majority of thesis regulations expect English quotations to be kept in the original. The reason is practical: in almost every discipline, current research is in English, and translating would only introduce a source of error.
What that looks like in practice (APA 7, German thesis)
Kahneman describes intuitive thinking as “fast, automatic, frequent, emotional, stereotypic, unconscious” (Kahneman, 2011, p. 21).
No translation note, no footnote, no explanation. The quotation stands as is. Everything around it is in German (or your thesis language) — only the quoted words themselves are English.
Two exceptions
1. Very long English block quotations. Some departments prefer that block quotations over three lines carry a translation in the footnote — not as a replacement, but as reading support. Check your department’s guide.
2. English terms that already have an established equivalent. “Boundary layer” becomes “Grenzschicht” in a German engineering thesis; “supply chain” becomes “Lieferkette”. Where the target-language technical vocabulary exists, you use it in your own prose — but the word-for-word quotation keeps the English original.
Other widely read languages — French, Spanish, Italian
For the major European languages the answer depends on your field:
- Humanities (literature, history, philosophy, Romance studies): original quotation stays, no translation. If you study French literature, you will not translate the primary text into your thesis language.
- Business, law, engineering: translation is customary, usually with the original in the footnote.
- Social sciences: inconsistent. Ask the department if the guide is silent.
Example — French source, English thesis (translation in text, original in footnote)
Piketty argues that capital concentrates more strongly than labour¹ (Piketty, 2013, p. 47).
¹ In the original: “le capital se concentre plus fortement que le travail.”
The note “translated by the author” can be dropped from individual quotations if you set a blanket statement in your methodology chapter: “Unless indicated otherwise, all foreign-language quotations were translated from the original by the author.”
Less familiar languages — Russian, Chinese, Arabic, Japanese
For languages your readers cannot be assumed to read, translation is the default. Two variants appear in practice:
Variant A — translation in text, original in footnote:
The ministry report describes the reform as a “fundamental restructuring of the education system”¹ (Ministry of Education, 2019, p. 8; translated by the author).
¹ In the original: “基础教育体系的根本重组”.
Variant B — translation only, with a note:
The ministry report describes the reform as a “fundamental restructuring of the education system” (Ministry of Education, 2019, p. 8; translated by the author).
Variant A is more precise and mandatory in humanities and area studies. Variant B is accepted in applied fields where a word-for-word check of the source is not central to the argument.
How to phrase the translation note
There is no single formula, but four variants are common and accepted by any second examiner:
- “translated by the author”
- “trans. by the author”
- “author’s translation”
- “own translation”
The note goes at the end of the quotation, immediately before the closing bracket or in the footnote. If your thesis contains many translated quotations, save yourself the repetition with a statement in the methodology chapter:
“Unless otherwise indicated, all foreign-language quotations have been translated from the original source language into English by the author.”
That blanket note replaces the individual marker under each quotation.
Working with existing published translations
If a recognised translation of your source already exists, the situation changes. Two paths are possible:
Path 1: Cite the translation as its own source. The translator appears in the bibliography, with the original mentioned only as context:
Heidegger, M. (1962). Being and Time (J. Macquarrie & E. Robinson, Trans.). New York: Harper & Row.
Path 2: Cite the original and note the translation. Common in humanities when the original is the actual object of study:
Heidegger, M. (1927): Sein und Zeit. Tübingen: Niemeyer. (English translation: Being and Time, trans. J. Macquarrie & E. Robinson, New York 1962).
Which path fits depends on whether you are doing close reading (Path 2) or arguing from content (Path 1).
The most common mistake: translating without marking
The worst pattern in examiner practice: a student finds an English quotation, translates it into the thesis language, puts it in quotation marks and references the original as if it were a same-language quotation. To the examiner this looks like a false citation: at the referenced page there is a different wording than in the thesis.
Two rules prevent this:
- Visible marking. Translation note on the quotation itself, or a blanket sentence in the methodology chapter — one of the two, always.
- Original in the bibliography. The work you actually used belongs in the reference list, not your rendering of it.
If either element is missing, the translation will in doubt be scored as a false citation, even when the content is accurate.
Machine translation — DeepL, ChatGPT and co.
The question comes up more and more: is it acceptable to use DeepL for quotation translation? Short answer: yes, as a tool. Longer answer requires two cautions.
First: verify every machine translation. For general prose DeepL is reliable; for technical terminology it is systematically weaker. Typical failure modes:
- Negations dropped. “should not” becomes “should” — rarer than a few years ago, but still.
- Technical terms translated literally. “significant” becomes “bedeutend” (important) in a German target, when “signifikant” (statistically significant) was intended.
- Modal verbs shifted. “may” becomes “can”, flattening the epistemic hedge in the original.
Second: declare AI use where required. Many German, Swiss and Austrian universities in 2026 require that the use of AI tools be disclosed in the author’s declaration — translation aids included. One sentence is enough: “DeepL Pro was used as an aid for translating foreign-language quotations; the translations were checked against the original texts and adjusted where necessary.”
Our post AI in higher education covers disclosure obligations in more detail.
Special case: classical works with established translations
For canonical authors (Aristotle, Kant, Marx, Weber, Confucius) the convention is: cite the established translation when writing in your thesis language and that translation is the standard. Fresh translations are their own scholarly work and are cited like ordinary secondary literature.
Example — Marx in an English thesis:
Marx writes: “The philosophers have only interpreted the world in various ways; the point is to change it” (Marx, 1845/1976, p. 5, in the Collected Works, Vol. 5).
The reference to the Collected Works edition is standard practice and replaces naming the original manuscript.
Special case: transliteration and diacritics
Sources in scripts other than Latin (Cyrillic, Arabic, Chinese, Devanagari) present a separate question: transliterate or preserve the original script? Three points of guidance:
- Bibliography: most style guides now accept the original script. If your typesetting supports it (LaTeX with XeLaTeX or LuaLaTeX, Word with an appropriate font), keep the original. Otherwise use a documented transliteration standard (Pinyin for Chinese, ISO 9 for Cyrillic, ALA-LC for Arabic).
- In-text citation: in most styles, the author-year reference uses the transliterated form even when the bibliography preserves the original script.
- Quoted material: follow Variant A above — original script in the footnote, translation in the text.
Do not mix transliteration standards within a single thesis. Pick one per language and hold it consistent.
Checklist before submission
Before you submit, walk through every foreign-language quotation:
- Does the original text in the source actually match the wording I am quoting?
- Have I marked the translation (individually or via a blanket sentence)?
- Does the original source — not my translation — appear in the bibliography?
- Are the language boundaries in the text consistent (target language / source language)?
- If I used DeepL or ChatGPT: is that disclosed in the author’s declaration?
A quotation that fails any one of these five checks will trigger an awkward question in the oral defence.
Where Acurio comes in
The hardest part of citing from a foreign language is not the formality — it is content accuracy. And this is exactly where the machine-translation failure modes from the section above land: a negation DeepL swallows, or a modal verb that slips from “may” to a flat assertion, changes what your quotation claims — usually without you noticing on a quick read-through.
A concrete example:
- Original (English): “The results may indicate a shift in consumer behaviour.”
- Translation (DeepL, unchecked): “Die Ergebnisse zeigen einen Wandel im Konsumverhalten.” — in other words, “the results show a change in consumer behaviour.”
The hedged possibility (“may indicate”) has become a definitive finding (“show”). In a thesis where this source carries a key argument, that is not a detail: an examiner who checks the original finds a claim stronger than the source supports.
This kind of drift is what Acurio surfaces. The workflow:
- Upload your document. Upload the thesis (PDF or Word); for a first look, the bibliography alone is enough.
- Automatic claim-vs-source check. Acurio compares every citation against the original source — even when source and citation are in different languages — and checks whether the claim in your text is supported by what the source actually says.
- Per-citation findings list. You get a finding for each citation: supported, imprecise, or unsupported — with the passage where the original and your wording diverge.
To be clear about the limits: Acurio does not replace knowing the citation rules. The tool checks the content level — whether the source exists and whether it says what you claim — not the formalities: quotation marks, translation notes and footnote formatting remain your job.
For a first impression without signing up: the Quick Check checks your bibliography directly in the browser.
Conclusion
Citing foreign-language sources is less difficult than it sounds once three principles are in place: original in the bibliography, translation visibly marked, and any machine tools verified and disclosed. The question of whether to translate at all is field-dependent — ask your department when in doubt, but never pass off your own translation as an original-language quotation. Get those basics right and you can bring any source — English, French, Russian, Chinese, Arabic or Japanese — cleanly into your thesis.