The Publication Manual of the American Psychological Association provides detailed guidelines for creating citations in the APA style.
The first printing of the 2009 edition included numerous errors. Click here for a PDF listing of the problems.
The following links reflect information related to the 6th, (current) edition of the APA manual.
Here are a few things to look for:
1. APA Style applies to both your in-text citations and reference list, AND ALSO your paper's formatting.
2. If you are utilizing a source in your reference list there must be at least one in-text citation for that source. Similarly, if you have a source as an in-text citation it must be listed in the reference page.
Zotero is a free Firefox addon that collects, manages, and cites research sources. It's easy to use, lives in your web browser where you do your work, and works with all style citations. This citation tool also allows you to attach PDFs, notes and images to your citations, organize them into collections for different projects, and create bibliographies.
It automatically updates itself periodically to work with new online sources and new bibliographic styles.