1. The incidence of multiple births in man and some other unipara;Guttmacher;Obstet Gynecol,1953
2. Twinning in Yoruba women;Knox;J Obstet Gynaecol Br Emp,1960
3. Frequency of multiple birth in three cities of Japan;Inouye;Am J Hum Genet,1957
4. Multiple pregnancy;Benirschke;N Engl J Med,1973
5. Multiple pregnancy;Benirschke;N Engl J Med,1973