We're often asked "how do I reference something I read about in another book / article?"
Citing a quotation (or the ideas of a specific theorist) that has been found in another source is known as secondary referencing.
The primary source is the original source of the idea, theory or concept.
A secondary source is a quote or citation from an author who has appeared in another author’s work.
For example:
Marshall published an original theory in 1999 and Harrison wrote about that theory in their publication in 2011. You read about the theory in Harrison’s publication and you want to discuss the theory in your assignment. Here, Marshall (1999) is the primary source and Harrison (2011) is the secondary source.
If you can, it's good academic practice to find a copy of the primary source and use that. However this may not always be possible, so you may need to use secondary referencing.
In secondary referencing you must acknowledge both authors in-text. However, in your reference list you should only include the details of the source you have in front of you (the secondary source), which in this is case Harrison (2011).
You can phrase this in a number of ways, but you must clearly show that one author is citing the other. For example:
Marshall (1999) suggests … (as cited in Harrison, 2011, p. 47).
Marshall (1999), as cited in Harrison (2011, p. 47), found that ...
It was found (Marshall, 1999, cited in Harrison, 2011, p. 47) that ...
If you decide to quote the primary source, Marshall (1999), you will need to show this quote by using the double quotation marks and include the page number/s. The page number should come from the source that is front of you (secondary source), in this case Harrison’s (2011) book.
Marshall (1999) stated that "....." (as cited in Harrison, 2011, p. 47).