APA (7th ed.) Citation

WILLIAMS OBSTETRICS & COX, S. M. [. (2002). Williams obstetrics: Study guide.-- ed.21. McGraw-Hill.

Chicago Style (17th ed.) Citation

WILLIAMS OBSTETRICS and Susan M. [et.al] COX. Williams Obstetrics: Study Guide.-- Ed.21. New York: McGraw-Hill, 2002.

MLA (9th ed.) Citation

WILLIAMS OBSTETRICS and Susan M. [et.al] COX. Williams Obstetrics: Study Guide.-- Ed.21. McGraw-Hill, 2002.