These guidelines will get you started. You should double-check the Publication manual of the American Psychological Association, 6th edition, for the final word on APA style. The APA Manual is located in all University of Alberta libraries (PE 1475 A52 2010), usually in the Reference section of the library or at the service desk.
Every source cited in the text of your paper should have a corresponding entry in your reference list, with a few exceptions:
To cite a personal communication (such as a letter, email, text, or message you've received), include an in-text citation formatted as follows: (Author, personal communication, June 15, 2012). No reference list entry!
To cite a website, or a social media feed, such as a Facebook or Twitter page, simply include the URL in brackets (http://www.facebook.com/CouttsLibrary).
Note: If you are citing a particular webpage, tweet or Facebook post, rather than the site or feed as a whole, a reference list entry IS required. See our page on Citing Web Resources for more details.