Secondary Source Citation APA: The As Cited In Rule, With Examples
How to cite a source you found inside another source in APA 7: the as cited in format, what goes in the reference list, unknown years, quotes, and when to find the original.
Secondary source citation, APA style: name the original work, write "as cited in", then name the source you actually read. APA's own example is (Rabbitt, 1982, as cited in Lyon et al., 2014). Only the source you read goes in your reference list. APA also asks you to cite secondary sources sparingly and to read the original whenever you can.
The rules below come from APA Style's page on secondary sources, which covers Section 8.6 of the seventh edition Publication Manual. The rest of this guide shows how to apply them in a thesis, and how to decide whether you should be using "as cited in" at all.
Primary and secondary sources in APA terms
APA defines the two kinds simply. A primary source "reports original content", and a secondary source "refers to content first reported in another source."
So the label depends on what you take from the work. A review article is a primary source for its own conclusions. It becomes a secondary source the moment you cite it for a finding it reports from someone else's study.
Secondary source citation: APA format in three steps
You need three decisions: what to write in the text, whether to include the original year, and what to put in the reference list. APA's page gives a rule for each.
- In the text, "identify the primary source and write 'as cited in' the secondary source that you used."
- For the year, include the primary source's year if you know it. If you do not know it, leave it out.
- In the reference list, "provide an entry for the secondary source that you used." The primary source gets no entry.
The forms APA shows
| Situation | Example from APA's page | What is in the reference list |
|---|---|---|
| Year of the original is known | (Rabbitt, 1982, as cited in Lyon et al., 2014) | Lyon et al. (2014) only |
| Year of the original is unknown | Allport's diary (as cited in Nicholson, 2003) | Nicholson (2003) only |
The second example also shows a narrative form, with the original named in your sentence and the "as cited in" part in parentheses. APA's page does not print a narrative version with both years, so if your sentence needs one, keep to the same pattern and ask your supervisor if your department has a preference.
Names and "et al." on both sides
The usual author rules apply to each name in the citation. APA's author and date guidance says to use the first author plus "et al." for three or more authors. It applies "in every citation (even the first citation)", which is why APA's example reads "Lyon et al." rather than a list of every author. With two authors, use "&" inside parentheses and spell out "and" in running text.
A worked example, before and after
Here is the situation APA's page describes, set out as you would meet it while writing. You are reading Lyon et al. (2014), and on one page they report a finding from Rabbitt (1982). You cannot get hold of Rabbitt's paper.
| Draft | Problem | Fixed version |
|---|---|---|
| ...as Rabbitt (1982) found. | Implies you read Rabbitt | ...as reported in earlier work (Rabbitt, 1982, as cited in Lyon et al., 2014). |
| Rabbitt (1982) and Lyon et al. (2014) both in the reference list | Lists a work you did not read | Lyon et al. (2014) only |
| (Lyon et al., 2014) for Rabbitt's finding | Credits Lyon et al. with Rabbitt's result | (Rabbitt, 1982, as cited in Lyon et al., 2014) |
The reference list entry for the secondary source follows the normal format for its type. If it is a journal article, model it on APA's journal article reference examples. Here is a fill-in template; replace every placeholder with the real details.
Author, A. A., Author, B. B., & Author, C. C. (Year). Title of the article. Journal Name, volume(issue), page range. https://doi.org/(DOI)
That same page says to always include the issue number. It also says to include a DOI whenever the article has one.
When to use a secondary source, and when to avoid it
Use "as cited in" only when you truly cannot read the original. APA's page tells you to "cite secondary sources sparingly" and names three situations where it fits.
- The original work is out of print.
- The original is unavailable.
- The original is available only in a language you do not understand.
Outside those cases, APA says to find, read and cite the original rather than citing a lecture, textbook or encyclopedia that in turn cites original research. The exception is when your instructor directs otherwise.
A quick decision check
Run each "as cited in" in your draft through these questions before you submit. Work down the rows in order.
| Question | If yes | If no |
|---|---|---|
| Have you searched for the original by title and author? | Go to the next question | Search first, using the steps below |
| Can you get it through your library, including an interlibrary loan request? | Read it and cite it directly | Go to the next question |
| Is it out of print, unavailable or in a language you cannot read? | Use "as cited in" | Keep looking, or ask a librarian |
| Is the point central to your argument or method? | Make extra effort to read the original | A secondary citation may be acceptable |
The last question is a judgement call, not an APA rule. In a thesis, the claims your argument rests on are the ones an examiner is most likely to follow back to the source.
How to find the original before settling for "as cited in"
Most of the work is copying the right details out of the secondary source. Its reference list should give you the original's authors, year, title and where it was published.
- Find the original in the secondary source's reference list and copy the full entry.
- If the entry has a DOI, open it and check that the work it shows matches the entry.
- If there is no DOI, search the title in your library catalogue and a subject database.
- For an older paper, follow our guide on how to find the DOI for an old paper.
- Once you have the original, check every detail against the real record, as set out in our guide to checking if a citation is real.
Step 5 matters because you are relying on another author's reference list. If they copied a year or title wrongly, your citation inherits the mistake. Reading the original also lets you confirm it says what the secondary source claims.
Quoting words you found in a secondary source
Paraphrase if you can. APA's quotations guidance says it is "best to paraphrase sources rather than directly quoting them," and that a direct quotation must include the page number or other location.
APA's secondary sources page does not say whose page number to give when you quote the original through a secondary source. The only page you have seen is in the secondary source. If you must quote, ask your supervisor how your department wants it shown, or find the original and quote from that.
What Thesisroom does with this
Thesisroom's Citation Check looks each reference up in eight registries: Crossref, OpenAlex, Semantic Scholar, PubMed, Retraction Watch, DOAJ, CORE and Unpaywall. It shows which references it could verify, which are retracted, and which need checking by hand. With an "as cited in" citation, the secondary source is the one in your reference list, so that is the entry it checks.
Whether you should have read the original is a decision Thesisroom leaves to you. For a full pass over your list before submission, see our guide to thesis defense reference list checking.
Frequently asked questions
Do both sources go in the APA reference list?
No. APA says to give a reference list entry only for the secondary source you used. The original work appears in your text, after which you write "as cited in" and the secondary source.
What if I do not know the year of the original work?
Leave it out. APA's example is "Allport's diary (as cited in Nicholson, 2003)". Include the original's year only when it is known.
Is "as cited in" acceptable in a thesis?
APA Style allows it but says to use it sparingly: when the original is out of print, unavailable, or in a language you do not understand. Your university or supervisor may set stricter expectations, so check before relying on it often.
Can I cite a textbook for a study it describes?
APA advises against it. Rather than citing a textbook, encyclopedia or lecture that cites original research, find, read and cite the original research, unless your instructor tells you otherwise.
Where is the secondary source rule in the APA manual?
APA Style's website says the guidance is in Section 8.6 of the seventh edition Publication Manual, and in the Concise Guide. The website page gives the same rules and examples.
Should I use et al. inside an "as cited in" citation?
Yes, for any work with three or more authors. APA says to give the first author plus "et al." in every citation, including the first. That is why APA's example reads "as cited in Lyon et al., 2014".
Sources
- APA Style: Secondary sources
- APA Style: Author and date in in-text citations
- APA Style: Journal article references
- APA Style: Quotations
How this guide was made: Thesisroom drafted this guide with the help of AI writing tools, then checked every fact, figure and source by hand against the references linked above.