1. Pritchard JA, MacDonald PC: Williams Obstetrics, 16th ed. New York, Appleton-Century-Crofts, 1980
2. Danforth DN: Obstetrics and Gynecology, 3rd ed. New York, Harper and Row, 1977
3. Sleisenger MH, Fordtran JS: Gastrointestinal Disease, 2nd ed. Philadelphia, WB Saunders, 1978
4. Bockus H: Gastroenterology, 3rd ed. Philadelphia, WB Saunders, 1976
5. Kleckner MS, Bargen JA, Banner EA: Chronic ulcerative colitis and pregnancy. Am J Obstet Gynecol 62:1234?1242, 1951