APA style is typically used by researchers in the social sciences, and its basic reference handbook is the "Publication Manual of the American Psychological Association." The manual itself may prove a useful research source, depending on the topic. APA style, 6th edition, calls for a references list that includes every source used in a research paper but only those sources.
Citing a book in the references list calls for the author's surname first, followed by the first initial, the publication date in parenthesis, the title in italics with only the first word capitalized and the publication location and publisher name, separated by a colon. Separate major elements with periods. The APA handbook, however, does not have a single author, so you must adjust the format, giving the name of the organizational author instead.
The full citation for the APA handbook will, like all entries in the references list, use hanging indent, with the second and later lines indented by 1/2 inch. For example:
American Psychological Association. (2009). Publication manual of the American Psychological Association. (italics) Washington, D.C.: American Psychological Association.