About APA
The American Psychological Association sets the rules for APA citation. The best scientific writing is spare and straightforward. It spotlights the ideas being presented, not the manner of presentation. Manuscript structure, word choice, punctuation, graphics, and references are all chosen to move the idea forward with a minimum of distraction and a maximum of precision.
To achieve this clarity of communication, publishers have developed rules of style. These rules are designed to ensure clear and consistent presentation of written material. Editorial style concerns uniform use of such elements as punctuation and abbreviations, construction of tables, selection of headings, citation of references, and presentation of statistics.
When editors or teachers ask you to write in APA Style®, they are referring to the editorial style that many of the social and behavioral sciences have adopted to present written material in the field. APA Style was first developed 80 years ago by a group of social scientists who wished to establish sound standards of communication. Since that time, it has been adopted by leaders in many fields and has been used by writers around the world.
Books on APA Citation
Concise Guide to APA Style by 
Publication Manual of the American Psychological Association by 