Secondary Citations Explained: Citing a Source You Have Not Read

Academic reading leads you down chains. You read an article that quotes an earlier study, and you want to use that finding. You find a textbook summarizing a theory, and you want to refer to the person who proposed it. The question is how to credit the original without pretending you read it.

The answer is a secondary citation. It is a small, honest convention, and it is easy to get wrong. This guide explains when it is appropriate, how to write it in several styles and why finding the original is usually better. The examples use invented sources to show the format.

What a secondary citation is

A primary or original source is the work in which an idea, finding or quotation first appeared. A secondary source is a work that reports, summarizes or interprets that original.

A secondary citation is used when you want to refer to the original, but you have only read about it in a secondary source. In the text, you name the original and show that you learned of it through the other work. In the reference list, you list only the work you read.

The point is honesty: your reader should know which works you read yourself and which you know through someone else.

Why you should prefer the original

Secondary citations are allowed, but they come with risks.

• Errors travel. The secondary author may have misquoted, misread or oversimplified the original.
• Context is lost. A quotation can change meaning when removed from its setting.
• Markers read it as a shortcut. A paper full of "as cited in" suggests limited reading.
• You cannot check the claim. If you cannot see the original, you cannot be sure.

For these reasons, many instructors say to use secondary citations only when the original is truly unavailable. If you can find it through your library, interlibrary loan or a database, read it.

When a secondary citation is reasonable

• The original is out of print or very hard to obtain.
• The original is in a language you cannot read, and the secondary source translates it.
• The original is an unpublished or archival source that only the secondary author saw.
• You are discussing how one author interpreted another, and the interpretation is the point.
• You are limited by time on a minor point, and your instructor allows it.

For the main claims of your argument, the original is almost always better.

How to write a secondary citation

The pattern is the same across styles: name the original in your sentence, say "as cited in" or the style's equivalent, and cite the source you read.

APA 7

In the text, give the original author and year if known, then "as cited in" and the source you read.

Lee's study on spacing effects (as cited in Patel, 2020) found improvements in retention.

Lee (2015, as cited in Patel, 2020) argued that spacing works better than massing.

In the reference list, include only Patel (2020). If you quote, add the page from the source you read: (Lee, 2015, as cited in Patel, 2020, p. 45).

MLA 9

MLA uses "qtd. in" for a quotation you found in another source.

Lee argues that "spacing sessions improves retention" (qtd. in Patel 45).

In Works Cited, list only Patel. MLA advises using the original where you can.

Harvard (common pattern)

Lee (2015, cited in Patel 2020) argues that spacing improves retention.

Or parenthetically: (Lee 2015, cited in Patel 2020, p. 45). The reference list includes only Patel (2020). Check whether your university uses "cited in" or "quoted in".

Chicago notes-bibliography

In a note, give the original details as far as you know them, then "quoted in" or "cited in" and the full citation of the source you read.

1. Jordan Lee, quoted in Rina Patel, Reading in the Digital Age (Harbor Press, 2020), 45.

The bibliography lists only Patel. Chicago encourages you to cite the original wherever possible.

Numbered styles

In IEEE, Vancouver and AMA, you cite the work you read with its number, and name the original author in the text: "Lee's study, described in [3], found...". The reference list gives only the work you read.

Quoting through a secondary source

If the secondary source quotes the original and you want to use that quotation, you have two safe options.

1. Quote the original's words, marking them clearly, and use the secondary citation to show that you found them in the other source.
2. Paraphrase the idea and cite it as a secondary citation.

Use the page number of the source you read, since that is where your reader can check it. Do not use the page number of the original unless you have seen it yourself.

How to track down the original

Before you settle for a secondary citation, try these steps.

1. Look at the reference list of the secondary source to identify the original.
2. Search your library catalog and databases by title and author.
3. Use Google Scholar, which often links to open or library copies.
4. Ask a librarian. They can often get a copy through interlibrary loan.
5. Check for a newer edition or reprint that is easier to find.

If you find it, read the relevant part, check that the secondary source represented it fairly and cite it directly.

What not to do

• Do not cite a source you have not read as if you had read it. That is a form of misrepresentation.
• Do not copy the secondary source's reference list entry for the original into yours.
• Do not copy a quotation and its citation from a secondary source without saying where you found it.
• Do not build a paper on secondary citations for major claims.

If you only saw a source mentioned and are not sure what it says, leave it out.

Secondary citations and plagiarism

A secondary citation done properly is honest. Copying a chain of sources from someone's reference list without reading them, and citing them as if you had, is a form of citation misrepresentation, and some institutions treat it as an integrity issue. Our guide to avoiding plagiarism covers the wider principles of honest attribution.

A worked example

Suppose you read a textbook by Patel (2020) that says: "Lee (2015) showed that students who space their study sessions retain more information." You want to use this in your essay.

• If you cannot find Lee (2015): write "Spacing sessions improves retention (Lee, 2015, as cited in Patel, 2020)." List Patel (2020) only.
• If you find and read Lee (2015): write "Spacing sessions improves retention (Lee, 2015)." List Lee (2015), and, if you also used Patel, list that too.

The second version is stronger because it shows you read the original.

Summaries of research in textbooks

Textbooks and review articles summarize many studies in a few sentences, which makes them tempting to cite secondhand. Treat their summaries as a pointer, not as proof. If a point is central to your argument, locate the original study and read its method and results, since a textbook sentence can omit limits that matter.

Common mistakes

• Listing the original in the reference list when you did not read it.
• Leaving out "as cited in" and implying direct reading.
• Using the original's page number from the secondary source's quotation.
• Overusing secondary citations.
• Citing the wrong source as the one you read.
• Misrepresenting the original by trusting a weak summary.

A quick checklist

• Did I try to find the original?
• Is the secondary source clearly indicated in the text?
• Is only the source I read in the reference list?
• Is the page number from the source I read?
• Is this a minor point, not a central claim?

Final thoughts

A secondary citation is a way of being honest about how you know what you know. Use it when you must, prefer the original when you can, and always make clear which work you actually read. Readers value that honesty, and so do markers.