1. Pregnancy at 40 years and over;Biggs;Med J Aust,1973
2. Pregnancy in women over forty;Horger;Obstet Gynecol,1977
3. Pregnancy and delivery in women aged 40 and over;Kajanoja;Obstet Gynecol,1978
4. Grand multiparity in Greece;Lolis;Eur J Obstet Gynecol Reprod Biol,1978
5. Schwangerschaft und Geburt bei der Vielgebärenden;Meier;Geburtshilfe Frauenheilkd,1979