You will find a more detailed discussion of the style and additional examples in the print copy of the manual (Call Number BF76.7 .P83 2010) that is located by the reference desk on the 2nd floor of the library.
The American Psychological Association (APA) requires its authors to follow specific style and formatting rules. Articles published in APA journals all follow APA style.
From the Lloyd Sealy Library:
From the Purdue Online Writing Lab (OWL):
The APA makes an effort to keep their manual up to date. In between editions, however, new information sources emerge. This blog fills in the gap. Search its contents to see how you should cite Twitter, Facebook, and a host of other new media sources.