The Publication Manual of the American Psychological Association is quite thorough, but occassionally it may not have a specific rule for some types of sources. In this case, it is fine to use your own judgement based on what you know about existing APA Style rules. APA's own site says:
"In general, a reference should contain the author name, date of publication, title of the work, and publication data. When you cannot find the example reference you need in the Publication Manual of the American Psychological Association, choose the example that is most like your source and follow that format. Sometimes you will need to combine elements of more than one reference format. (APA, 2011, Frequently Asked Questions)."
American Psychological Association (2011). Frequently asked questions about APA Style. Retrieved from http://www.apastyle.org/learn/faqs/example- reference.aspx