These are links to a few sites that will help you format citations for the APA style. Most of the electronic resources you use will have an easy link to show you what the citation will look like in an APA format. But always remember, the instructor is the last word on the correct format for the citation.
Mary Livermore Library Refworks Page
APA Citation Style Guide from Cornell University
APA Formatting and Style Guide from the OWL at Purdue University
APA Documentation from the University of Wisconsin