APA-referens (7:e uppl.)

Callen, P. W. (1988). Ultrasonography in obstetrics and Gynecology (2.ed.). Saunders Company.

Chicago-referens (17:e uppl.)

Callen, Peter W. Ultrasonography in Obstetrics and Gynecology. 2.ed. Philadelphia: Saunders Company, 1988.

MLA-referens (9:e uppl.)

Callen, Peter W. Ultrasonography in Obstetrics and Gynecology. 2.ed. Saunders Company, 1988.