1. Maternal states in relation to congenital malformations;Carter, C. 0;J. Obstet. Gynaec. Brit. Emp,1950
2. Congenital abnormalities;Coffey, V.P.; Jessop, W.J.E.;Irish J. med. Sci,1955
3. Missbildungshaufigkeit und Gebaralter;Hegnauer, H.,1951
4. Personal communication, quoted by Penrose;Kahn, E.,1956
5. Kahn, E. (1957).