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.
Egan published an original theory in 2006 and Geldard and Geldard used that theory in their publication in 2007. You read about the theory in Geldard and Geldard’s publication and you want to discuss the theory in your assignment. Here, Egan (2006) is the primary source and Geldard and Geldard (2007) is the secondary source.
You must acknowledge both groups of authors in-text. However, in the reference list you will only include the details of the source you have in front of you (the secondary source), in this case Geldard and Geldard (2007).
Egan (2006) suggests … (as cited in Geldard & Geldard, 2007).
If you decide to quote Egan (2006), you will need to show this quote by using the double quotation marks and include the page number/s. Again the page number should come from the source that is front of you (secondary source), in this case Geldard and Geldard’s (2007) book.
Egan (2006) stated that "....." (as cited in Geldard & Geldard, 2007, p. 9).