You didn't mention what citation style you're using. If it's APA, their blog has a nice post on this question that includes examples:
APA Secondary Sources ( “as cited in”)
If you're using MLA, the Purdue Owl page has some instructions under their "Formatting Quotations" section.
Additionally, you can look at this page from Utica University for examples of citing secondary sources.
As the pages indicate, it's generally preferable to use the original source, no matter which style you're using. If you need help finding the original article (or if you're using some style other than APA or MLA), please feel free to get back to me with the details.
