Penrose, L.S. : Familial data on 144 cases of anencephaly, spina bifida and congenital hydrocephaly. Ann. Eugen. (London) 13: 73, 1946.
2.
Record, R.F. and McKeown, T.: Congenital malformations of the central nervous system; III. risk of malformations in siblings of malformed individuals. Brit. J. Soc. Med.4: 217, 1950.
3.
MacMahon, B. , Pugh, T.F. and Ingells, T.H.: Anencephaly, spina bifida and hydrocephalus; incidence related to sex, race and season of birth, and incidence in siblings . Brit. J. Prev. Soc. Med.7: 211, 1952.
4.
Lorber, J.: The family history of spina bifida cystica. Pediatrics35: 589, 1965.
5.
Williamson, E.M.: Incidence and family aggregation of major congenital malformations of the central nervous system. J. Med. Genet.2: 161, 1965.
6.
Carter, C.O. , David, P.A. and Laurence, K.M.: A family history of major central nervous system malformations in South Wales. Ibid.5: 81, 1968.
7.
Smithells, R.W. , D'Arcy, E.E. and McAllister , E.F.: The outcome of pregnancies before and after the birth of infants with nervous system malformations . Develop. Med. Child. Neurol. Suppl. 15: 6, 1968.
8.
Lorber, J. and De, N.C.: Family history of congenital hydrocephalus. Ibid. In press, 1970.
9.
Carter, C.O. and Roberts, J.A.F.: The risk of recurrence after two children with central nervous system malformations. Lancet1: 306, 1967.
