1. The incidence of multiple births in man and some of the other unipara. Obstet Gynecol;Guttmacher, A.F.,1953
2. Secular changes in rates of multiple births in the United States;Jeanneret 0, MacMahon B;Am J Hum Genet,1962
3. Do conception delays explain some changes in twinning rates?;Allen, G.; Schachter, J.;Acta Genet Med Gemellol,1970
4. Some observations on the decline in the United States dizygotic twinning rate;Wyshak, G.;Soc Biol; Registrar,1975
5. Changing incidence of twinning in Scotland in 1939-68;MacGillivray, I.;Acta Genet Med Gemellol,1970