Citazione Stile APA (7a Edizione)

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

Citazione stile Chigago Style (17a edizione)

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

Citatione MLA (9a ed.)

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