Remember to cite not only direct quotes, but also other people's ideas. If you paraphrase something, changing a few words to make it sound less like a direct quote, you still have to cite it. If you are uncertain, it is better to cite a source than to be accused of plagiarism for not citing something you should have.
APA
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Publication Manual of the American Psychological Association (http://suncat.csun.edu/record=b2499930)
Reference Room BF76.7 .B83 2010
Reserve Desk BF76.7 .B83 2010
Floor2 BF76.7 .B83 2010 -
APA Style Guide (PDF) by Eric Garcia
http://library.csun.edu/egarcia/documents/apacitationguide.pdf