1. International Practice and Research, Baillieres;Campbell DM;Clin Obstet Gynaecol,1990
2. Pregnancy outcome in 625 cases of multiple pregnancy during the years (1980–1983);Legnain MM;Arab J Med,1986
3. Seventy-one quadruplet pregnancies: management and outcome;Collins MS;Am J Obstet Gynecol,1990
4. Emberazos Triplets. Una revision de 16 casos;Melchor JC;Rev Lat Am Ester Fert,1989