1. Unrecognised epidemic of anencephaly and spina bifida;lMacMahon B; S, Yen;Lancet,1971
2. Epidemic waves in the prevalence of anencephaly and spina bifida in New York State;Janerich, D.T.;Teratology,1973
3. Is myelomeningocele a disappearing disease? Pediatrics 1982; 69: 511-3. 4International Clearinghouse of Birth Defects Monitoring Systems. Annual report 1981;Stein, S.C.; Feldman, J.G.; Friedlander, M.; Klein, R.J.,1982
4. Congenital malformations of the central nervous system;Bradshaw, J.; Weale, J.; Weatherall, J.;Population Trends,1980
5. Neural tube defects;Nevin, N.C.;Lancet,1981