How to Cite a Secondary Source
Updated July 2026
A secondary source is when you cite a work you didn't read directly — you encountered it quoted or summarized inside another source. The rule: name the original, then credit the source you actually read with “as cited in.”
Best practice is always to find and read the original. But when you genuinely can't, here's how to cite it honestly in each style.
The format
APA in-text: (Ebbinghaus, 1885, as cited in Rasch & Born, 2013) MLA in-text: (qtd. in Rasch and Born 685)
You mention the original author (Ebbinghaus) so the reader knows whose idea it is, but you point to the source you read (Rasch & Born) because that's what you can actually verify. APA uses as cited in; MLA uses qtd. in (quoted in).
Only the source you read goes in the reference list
This is the part people get wrong: the reference list contains only the source you actually read — Rasch & Born, not Ebbinghaus. You never read Ebbinghaus, so you can't list it. Your in-text citation names both; your reference entry lists one.
Rasch, B., & Born, J. (2013). About sleep's role in memory. Physiological Reviews, 93(2), 681-766. https://doi.org/10.1152/physrev.00032.2012
In-text(Rasch & Born, 2013)
Why you should find the original
Secondary citing is a last resort. The source you read may have misquoted, oversimplified, or misinterpreted the original — and you'd be repeating their error under your own name. Reviewers also notice over-reliance on secondary sources. Search for the original by title or DOI; if it exists, cite it directly and drop the secondhand chain entirely.
When secondary citing is acceptable
Official guidance: APA's secondary-sources rule and the MLA Style Center. For anything you can access, read and cite it directly.
- The original is out of print, untranslated, or genuinely inaccessible.
- The original is a classic or archival work you can't reasonably obtain.
- You're explicitly discussing how the second author used the first (then the relationship is your point).
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Go Premium — $5/monthFrequently asked questions
- What does “as cited in” mean?
- It signals you're citing a source you didn't read directly — you found it referenced inside another source. You name the original author but credit the source you actually read: (Ebbinghaus, 1885, as cited in Rasch & Born, 2013).
- Which source goes in my reference list?
- Only the one you actually read (the secondary source). You never read the original, so you can't list it — your in-text citation names both, the reference list has just the one.
- Is “qtd. in” the MLA version of “as cited in”?
- Yes — MLA uses 'qtd. in' (quoted in): (qtd. in Rasch and Born 685). Same idea, different style's wording.
- Should I avoid secondary sources?
- Whenever possible, yes — find and cite the original, since the secondary source may have distorted it. Use secondary citing only when the original is genuinely inaccessible.