Why do we cite sources?
There are numerous reasons why such as:
(Ridley, 2012, p. 119)
When do you need to cite your sources?
It's easy: whenever you paraphrase the ideas of others, whenever you use a direct quotation, or whenever you cite a fact that isn't common knowledge, you need to cite your original sources, whether they are books, articles, or web site.
APA Style Tutorials
The following additional resources provide assistance in citing sources according the Publication Manual of the American Psychological Association (APA):