Answered By: Jeff Dowdy Last Updated: Nov 01, 2017 Views: 8
From the APA Style Blog (a great resource!):
You’ve probably heard that you should avoid secondary sources when possible. It’s true—if you find great information being quoted or paraphrased somewhere, it’s well worth your effort to track down the original source so you can read it for yourself and therefore cite it directly.
Read the rest of the article: Secondary Sources (aka How to Cite a Source You Found in Another Source).
Basically, if you can't track down the original, reference the original in your writing, yet reference the secondary in your in-text citation and reference list.