The American Psychological Association (APA) style guide was developed in 1929 by a group of academics who wanted to standardize the citing of sources in the social sciences. The disciplines that utilize APA style include social sciences such as Psychology, Linguistics, Sociology, Economics, and Criminology, as well as Business, Nursing, Education, and Library Science.
The most authoritative source on APA style is the APA style guide. It is available at UI Libraries:
You can easily capture a computer-generated citation from the library databases, InfoHawk+, and Google Scholar. I would also highly recommend this tool from ZoteroBib, a free, user-friendly, and accurate way to build a bibliography: