How to Cite a Source You Found Inside Another Source

You are reading Johnson's book, and Johnson quotes something Smith said that is perfect for your paper. You never read Smith. You cannot cite Smith as if you did, and you cannot pass Smith's idea off as Johnson's. The fix is a secondary citation, and both major style guides have a specific format for exactly this.

Getting it wrong is a quiet, common way to end up misrepresenting your sources, claiming to have read things you have not. Here is how to do it right in APA and MLA, and the one step both guides really want you to try first.

Try to find the original, genuinely

Both style guides open with the same instruction, and it is not throat-clearing. Track down Smith and read Smith directly.

On this, APA is firm and specific. Save the secondary citation for the genuine dead ends, when the original is out of print, unavailable, or in a language beyond you. The rest of the time, the expectation is that you go dig up the source and read it. That is partly ethics and partly self-protection. Borrow a quote secondhand and you are trusting a stranger got the framing right, kept the emphasis honest, and copied every word correctly, and you will never know if they did not.

So the honest first move is a real search for the original. Often it takes ten minutes and removes the problem entirely. The secondary citation is what you use when that search genuinely fails, not the default because chasing the source is more work.

The APA format

When you truly cannot reach the original, APA names the original in your sentence and attaches an "as cited in" pointer to the source you actually read.

In the text, it looks like this:

Rabbitt's early work on cognitive load (1982, as cited in Lyon et al., 2014) established the basic finding.

Include the original's year if you know it. If you do not, drop the year and keep the "as cited in" pointer. The rule that catches people is in the reference list: you list only the source you actually read. Lyon goes in your references. Rabbitt does not, because you never held Rabbitt in your hands. Your reference list is a record of what you read, not of every name you mentioned.

The MLA format

MLA does the same job with different machinery: the abbreviation "qtd. in," for "quoted in."

In the text, you name the original author and point to the source you read:

In Zukofsky's phrasing (qtd. in Costello 78), the object is never neutral.

And the Works Cited list follows the same logic as APA: only the source you actually read appears. The entry is for Costello, the book you held:

Costello, Bonnie. Marianne Moore: Imaginary Possessions. Harvard UP, 1981.

Zukofsky, the original author, is named in your sentence but does not get a Works Cited entry, because you did not read Zukofsky directly. The page number is Costello's page, where you found the quote, not a page in Zukofsky.

The rule underneath both

Strip away the format differences and APA and MLA are enforcing one principle: your bibliography lists what you actually read, and your sentence gives credit to whoever had the idea.

A single secondary citation does two jobs. In your sentence it credits the person who had the idea, so Smith does not get erased. In your reference list it names the book you genuinely read, so you are not faking a source. Lose one half and the whole thing tips over. Credit only Johnson and you have swallowed Smith's idea whole. Reference Smith and you are vouching for a book that never passed through your hands.

What "as cited in" versus "qtd. in" actually signals

The two abbreviations do the identical job, but their wording reflects a small difference worth understanding, because it tells you which one to reach for.

The two abbreviations do the same work, but their wording hints at when each fits best. MLA's "qtd. in" is literally "quoted in," and it suits the usual case where you lifted an exact quotation the author had dropped into the book you read. APA's "as cited in" reaches a bit further, covering a paraphrase your source made of the original as well as a straight quote. You can bend either one to cover both jobs inside its own style, but that difference in phrasing is a handy nudge: a secondary citation exists for any borrowed idea, not only a borrowed set of quotation marks. Paraphrase Smith by way of your source and it still needs the pointer.

Chains, and why they stop at two

Occasionally you hit a source that is itself citing a secondary source: Johnson quotes Brown quoting Smith. The temptation is to reproduce the whole chain, and you should not.

Cite the source you actually read, Johnson, and name the earliest original whose idea you are using, Smith, if Johnson makes it clear. You do not reconstruct a three-name chain in your citation, and you certainly do not present the middle link as something you read. If the chain is so tangled that you cannot tell who originated the idea, that is the strongest possible signal to go find the primary source and cite it directly, because you do not currently understand the provenance of what you are about to put in your paper.

Where people get it wrong

Four mistakes account for nearly all of them:

• Citing the original as if you read it. You put Smith in your references from a quote you found in Johnson. This is the most common error and the most serious, because it is a false claim about your own research.
• Dropping the original author entirely. You cite only Johnson, which quietly transfers Smith's idea to Johnson and to you.
• Listing both in the bibliography. Only the source you read belongs there. The original is named in the text alone.
• Using the original's page number. Your page reference points to where you found the quote, in the source you read, not to the original you never opened.

A quick decision path

When you find a quotation inside another source:

1. Can you find and read the original? If yes, do that, and cite it directly. This is the preferred outcome every time.
2. Genuinely cannot reach it? Use a secondary citation: name the original author in your sentence, add "as cited in" (APA) or "qtd. in" (MLA) pointing to the source you read.
3. Building your reference list? Include only the source you actually read. The original author lives in your text, never in your bibliography.

Why this is worth getting right

A secondary citation is a small piece of formatting that carries a surprisingly large honesty claim: it states precisely what you read and what you took on someone else's authority. Handled correctly, it is a mark of a careful writer, someone who did not pretend to sources they never touched.

And it walks you clear of one specific charge. Say you read a book you never opened, and that is dishonesty on its own terms, nothing to do with copying. The marker who chases a source you named, then realizes you could not possibly have read it, comes down about as hard as they would on a stolen paragraph. Get the secondary citation right and that scene never happens to you. If you are unsure whether a borrowed fact even needs this level of attribution, that is a separate question worth answering first, and once you know it does, the choice of quote, paraphrase, or summary follows the same rules as any other source.