Q. How do you cite the DSM-5 in APA (6th edition)?

The APA Style Blog -- the official blog of the APA Style Guide -- has guidelines for citing the DSM-5 in APA 6th edition.

Here's what a citation looks like:

American Psychiatric Association. (2013). Diagnostic and 
     statistical manual of mental disorders (5th ed.). Washington, DC: 
     Author.

Text citation: (American Psychiatric Association, 2013)

Individual chapters and other parts of DSM-5 have been assigned DOIs. If you used the online edition of the DSM, give the DOI in the publisher position:

American Psychiatric Association. (2013). Cautionary statement for 
     forensic use of DSM-5. In Diagnostic and statistical manual of 
     mental disorders (5th ed.). doi:10.1176/appi.books
     .9780890425596.744053

Text citation: (American Psychiatric Association, 2013)