Cunningham, F. G., Leveno, K. J., Bloom, S. L., Hauth, J. C., Gilstrap III, L. C., Wenstrom, K. D., & Williams, J. W. (2005). Williams obstetrics (22. edition.). New York: McGraw-Hill.

Cunningham, F. Gary, Kenneth J. Leveno, Steven L. Bloom, John C. Hauth, Larry C. Gilstrap III, Katharine D. Wenstrom, and John Whitridge Williams. Williams Obstetrics. 22. edition. New York: McGraw-Hill, 2005.

Cunningham, F. Gary, et al. Williams Obstetrics. 22. edition. New York: McGraw-Hill, 2005.