How to Cite a Source Cited in Another Source (APA, Harvard, MLA and Chicago, 2026)

A secondary citation (also called an indirect citation or secondary referencing) is a citation to a work you have not read yourself, which you know about only because a source you did read summarised or quoted it. The source you read is the secondary source; the work it mentions is the original.

When is it acceptable to cite a source I found in another source?

A secondary citation is acceptable when the original is genuinely out of reach, and that should be rare. APA 7 guidance, as reproduced by the Atlantic Technological University library, says to cite secondary sources "sparingly", for instance "when the original work is out of print, unavailable, or available only in a language that you do not understand" (Atlantic Technological University, APA 7 secondary sources). If the original is a 2019 journal article your library can get through interlibrary loan, "unavailable" does not apply.

The same guidance leads with the instruction most students skip: "If possible, find the primary source, read it, and cite it directly rather than citing a secondary source." Anglia Ruskin University’s Harvard guide is blunter: "it is best to avoid using secondary referencing" (Anglia Ruskin University, Harvard referencing).

The dishonest alternative is citing the original as if you read it. If Smith misquoted Johnson and you cite Johnson directly, you have put your name to Smith’s mistake.

How do I cite a source I found in another source in APA 7?

In APA 7, name the original work in your sentence or in the parentheses, then write "as cited in" followed by the source you actually read, its year, and a page number if you are quoting. Only the source you read appears in the reference list. The rule is section 8.6 of the Publication Manual (page 258), according to the Camosun College library’s APA 7 guide (Camosun College, indirect sources).

Purdue OWL’s version: "Name the original source in your signal phrase. List the secondary source in your reference list and include the secondary source in the parentheses" (Purdue OWL, APA in-text citations). Its two example forms:

• Johnson argued that... (as cited in Smith, 2003, p. 102).
• (Johnson, 1985, as cited in Smith, 2003, p. 102)

Two details trip people up. First, the year of the original: Camosun’s guide says "When the year of the indirect source is known, include it in the text"; if you do not know Johnson’s year, leave it out rather than guess. Second, the reference list: "Only the source you have in hand is the one that goes into your Reference list." Johnson gets no entry. For a quotation, the page number belongs to the source you read: in National University’s APA 7 example "(as cited in Bratton & Strittmatter, 2013, p. 432)", page 432 is Bratton and Strittmatter’s page (National University, APA 7 secondary sources).

A note on sourcing: the APA Style website’s own secondary sources page is the authority here, but it was not accessible when I checked, so the wording in this section comes from university library guides that reproduce it. Our APA citation format guide covers the rest of the rules.

How do I cite a source cited in another source in Harvard referencing?

In Harvard, write the original author and year, then "cited in" (or "quoted in" for a word-for-word quotation), then the author, year and page of the source you read. List only the source you read. Harvard is a family of styles, so the guide I am following is the Cite Them Right Harvard version published by the University of Wolverhampton library, with Stellenbosch and UNISA for South African comparison.

Wolverhampton gives two forms (University of Wolverhampton, secondary referencing):

• Harvey (2015, quoted in Lewis, 2018, p. 86) provides an excellent survey...
• White’s views on genetic abnormalities in crops (2014, cited in Murray, 2018)...

The two words are not interchangeable in Cite Them Right: "quoted in" when the secondary source reproduces the original word for word, "cited in" when it paraphrases or summarises. For the reference list: "Only reference the source you actually used." So Lewis (2018) and Murray (2018) get entries; Harvey and White do not.

South African universities use their own Harvard variants, and the punctuation shifts. Stellenbosch University’s Harvard (Stellenbosch) guide calls this a "Citation within citation (Secondary reference)" and formats it as "(Coates, cited in Lee, 1986:34)", with a colon rather than "p." before the page number and no year for Coates (Stellenbosch University, Harvard A to Z). Its instruction is "In the reference list, write the source that has been used", and the entry it shows is Lee’s article. UNISA’s CEMS Harvard guide takes the same position: only the source where you read about the original goes in the list, and "your text should make it clear that you have not read the original" (UNISA, CEMS Harvard guide).

Follow your own faculty’s guide, because a marker checking against the Stellenbosch format will flag "p. 34" where "1986:34" is expected. Our Harvard referencing guide walks through the main variants.

How do secondary citations differ across APA, Harvard, MLA and Chicago?

Every style agrees on the principle (read the original if you can, and be transparent if you cannot) but the wording, punctuation and reference list differ. The table lists only formats verified on an official style page or a university library guide.

Chicago is the outlier: the only style here that requires the original’s full details alongside the source you read, and the one that discourages the practice most strongly.

For MLA, the MLA Style Center’s post of 20 September 2023 on indirect sources gives the pattern: According to Alexander Pope, "A little learning is a dang’rous thing" (qtd. in Damrosch 239). The works-cited entry is for Damrosch’s book only, and the original author’s name "can appear in the prose, in the in-text citation, or in an endnote" (MLA Style Center, citing indirect sources).

For Chicago, the Chicago Manual of Style’s online Q&A points to paragraph 14.260: "To cite a source from a secondary source (‘quoted in . . .’) is generally to be discouraged, since authors are expected to have examined the works they cite." Then the exception: "If an original source is unavailable, however, both the original and the secondary source must be listed" (Chicago Manual of Style Q&A). The example note runs Louis Zukofsky’s 1931 Poetry article, page 269, "quoted in" Bonnie Costello’s 1981 book, page 78. I could not verify a Chicago author-date form on a primary page, so I have left it out. Our guide to citing sources in a research paper compares the base formats of six styles.

Why do supervisors and journals discourage secondary citations?

Secondary citations are discouraged because a citation is a claim that you examined the work, and a secondary citation admits you did not. The Chicago Manual of Style says so directly: the practice "is generally to be discouraged, since authors are expected to have examined the works they cite." UNISA’s CEMS Harvard guide frames it as a reading obligation: "Wherever possible, it is important to read the original work, but this may be difficult in some instances."

For a postgraduate literature review the objection is sharper, because a review’s value is your judgement of the primary evidence. If a chapter says "Study A found X (as cited in Review B)", a supervisor will ask why you did not read Study A when Study A is the thing you are supposed to be evaluating. In my experience, one or two secondary citations in a thesis for unobtainable works pass without comment; a dozen in a chapter on recent literature read as a shortcut.

Manchester Metropolitan University’s Cite Them Right Harvard page gives the advice that applies everywhere: "check with your tutor if it is acceptable to use secondary citations in your academic work" (Manchester Metropolitan University, Cite Them Right Harvard). Journals vary too, so read your target journal’s author guidelines before you submit.

How do I find the original source instead of citing it second-hand?

Take the full reference from the source you read, search the title in Google Scholar and your library catalogue, and request it through interlibrary loan if it is not held. Most secondary citations in postgraduate drafts are for works obtainable within a week, so they fail the APA test of "out of print, unavailable, or available only in a language that you do not understand".

Once you have the original, read the passage the secondary source pointed to, and read around it; often the original hedged a claim the secondary source stated flatly. Then cite the original directly and drop "as cited in". Our guide to paraphrasing in academic writing covers restating what you found without drifting into the secondary source’s wording.

If you truly cannot get it, apply the University of Wolverhampton’s Cite Them Right Harvard distinction (the original’s words, "quoted in"; its ideas as summarised, "cited in"), cite it that way and move on. One honest "cited in" beats a week lost to a 1962 conference proceeding.

How does Litrevu handle a citation that sits inside another paper?

Litrevu only cites the PDFs a researcher uploads, so a work merely mentioned inside one of those PDFs cannot become a reference in the draft. Litrevu is an AI literature review assistant that turns the papers a researcher has already gathered into a cited first draft, with every citation traceable to the uploaded source. Built in South Africa and co-founded by Samuel de Bruyn, Litrevu offers 800 words free with no credit card required, as of August 2026.

When an uploaded paper summarises an earlier study, the draft attributes the claim to the uploaded paper and flags the earlier study. Here is the shape of that, as a format illustration only, with placeholder tokens rather than real names or findings:

[Source 1] reports that an earlier study by (Author, Year) reached a similar conclusion in a different population. [Check: (Author, Year) is cited within [Source 1] and is not among the uploaded papers. Read the original before citing it, or cite it as "(Author, Year, as cited in [Source 1])".]

That is a format illustration, not a real output. The researcher then fetches the original and uploads it, or keeps the secondary citation in their own style’s format and takes responsibility for it. Either way the researcher reads every line, verifies every citation against the PDF, and rewrites the draft in their own words. Litrevu produces a starting point, not a submission.

Scite is stronger at showing whether later papers support or contrast a claim, and Research Rabbit is stronger at mapping the citation network that leads you to the original; Litrevu does neither. The checks in how to spot fake AI citations before you submit apply to secondary citations too, since an original you never saw can be wrong without you noticing.

Frequently asked questions

Do I put both sources in my reference list for a secondary citation?

In APA 7, Harvard and MLA, no: list only the source you actually read. Purdue OWL’s APA rule is to "List the secondary source in your reference list", and Anglia Ruskin’s Harvard guide says the list "should only contain works that you have read". Chicago notes-bibliography style is the exception, where the Chicago Manual of Style Q&A says "both the original and the secondary source must be listed" in the note when the original is unavailable.

What is the difference between "cited in" and "quoted in" in Harvard?

In Cite Them Right Harvard, as set out by the University of Wolverhampton library, "quoted in" is for a passage the secondary source reproduces word for word, and "cited in" is for an idea it paraphrases or summarises. APA 7 uses "as cited in" for both. Stellenbosch and Anglia Ruskin Harvard guides show only "cited in".

Do I include the year of the original source in an APA secondary citation?

Yes, when you know it. Camosun College’s APA 7 guide, following section 8.6 of the Publication Manual, says "When the year of the indirect source is known, include it in the text", giving "(Tuso, 2013, as cited in King et al., 2020, p. 52)". If the secondary source does not give the original’s year, omit it rather than guess.

Can I use a secondary citation in my thesis or dissertation?

Usually yes, for a small number of genuinely unobtainable works, but check your department’s rules first. Manchester Metropolitan University’s Cite Them Right Harvard page tells students to "check with your tutor if it is acceptable to use secondary citations in your academic work". UNISA’s CEMS Harvard guide expects your text to "make it clear that you have not read the original".