You might want to cite a piece of work mentioned or quoted within another author’s work. You should always try and find the original source and cite from that rather than the interpretation you have read, but if it's not feasible to do this you may cite as a secondary source. This is known as a secondary reference as you have not actually seen the original source yourself.

In the text of your essay or assignment cite both the original source and the secondary source. They both appear in the same citation and you need to use the words 'quoted in' or 'cited in' depending on whether the source gives a direct quotation from, or a summary of, the original:

Smith (2004, cited in Jones, 2007, p.63) outlined some of the different research philosophies.

or

"The four main research philosophies are Pragmatism, Positivism, Realism, Interpretivism" (Smith, 2004, quoted in Jones, 2007, p.63).

In the list of references or bibliography include the date and publication details of the piece of work, and then 'Quoted in:' or 'Cited in:' followed by the reference for the source you have actually seen:

Smith, R. (2004) How to research. Research Weekly, 12 (8) October, pp.17-20. Quoted in: Jones, F. (2007) Researching your dissertation. Research Today, 4 (6) March, pp.61-67.