American Psychological Association (APA) 6th Edition: Introduction
The APA Publication Manual provides rules for citing (or referencing) sources of information within the text of your essay and the proper format for the list of references at the end of the essay. For all essays and reports, you will be required to document (i.e., acknowledge) all the sources of information you have used. Although common knowledge does not need a citation, when in doubt always provide the citation.
Tip:
Always confirm with your professor what citation and referencing style is required. For full information about APA style, see the website:
http://www.apastyle.org/