1. Akesson, H.A.: Epidemiology and genetics of mental deficiency in a Southern Swedish population. Uppsala: University of Uppsala 1961.
2. Baird, Sir Dugald: Environmental and obstetrical factors in prematurity, with special reference to experience in Aberdeen. Bull. Wld. Hlth. Org. 26, 291–295 (1962).
3. Berg, J.M., Kirman, B.H.: Some aetiological problems in mental deficiency. Brit. med. J. 1959 II, 848–852.
4. Bernstein, B.: Language and social class. Brit. J. Sociol. 11, 271 (1960).
5. Butler, N.R., Bonham, D.G.: Perinatal mortality. London-Edinburgh: Livingstone 1963.