Cita APA (7a ed.)

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

Cita Chicago Style (17a ed.)

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

Cita MLA (9a ed.)

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