The Diagnostic and Statistical Manual of Mental Disorders (DSM) is a book listing various mental health diagnoses. It is published by the American Psychiatric Association (Note: a common student mistake is to attribute it to the American Psychological Association, which is not the same organisation). The current edition is the 5th edition and is known as DSM-5. The style below can be adapted to citing older editions.

Reference list:

There is no publisher given because the same organisation both wrote and published it. If you have a DOI number for the DSM-5 you can put it at the end of the reference.

DSM-5

American Psychiatric Association. (2013). Diagnostic and Statistical Manual of Mental Disorders (5th ed.).

Previous edition: DSM-IV-TR (2000)

American Psychiatric Association. (2000). Diagnostic and Statistical Manual of Mental Disorders (4th ed., text rev.).

Old edition: DSM-IV (1994)

American Psychiatric Association. (1994). Diagnostic and Statistical Manual of Mental Disorders (4th ed.).

DSM-III-R (1987)

American Psychiatric Association. (1987). Diagnostic and Statistical Manual of Mental Disorders (3rd ed., revised).

DSM-III (1980)

American Psychiatric Association. (1980). Diagnostic and Statistical Manual of Mental Disorders (3rd ed.).

The citation in your text will be:

(American Psychiatric Association, 2013). Once you define the abbreviation APA, you could also then use (APA, 2013)

or, if you have quoted directly,

(American Psychiatric Association, 2013, p.453).

If you have used the author's name in your sentence then only the year of publication, with a page reference if necessary, is placed after it in brackets, eg.

DSM-5 (American Psychiatric Association, 2013) suggests that ...

or, if you have quoted directly,

DSM-5 (American Psychiatric Association, 2013, p. 16) states that ...