The APA citation style guide is created by the American Psychological Association.
Below is a link to the APA Quick Guide that the BU Writing Centre has created. It's an overview of APA and gives some basic examples.
The Library has three copies of the Publication Manual of the American Psychological Association:
They can be found on Reserve, in the Reference Collection of the Main Library, and in the Music Library.
There are many online sites with information and examples of how to use APA style.
See these links: