1. A clinical and genetic study of 1,280 cases of mental defect;Penrose, L.S.;Medical Research Council Special Report Series
2. Mental handicap or learning disability. A critique of political correcness;Reid, A.H.;BrJ Psychiatry,1997
3. World Health Organiztion. Nature of the problem. Mental retardation: meeting the challenge;WIHO Offset Publication,1985
4. Aetiology of mild mental retardation;Lamont, M.A.; Dennis, N.R.;Arch Dis Child,1988
5. The recurrence risks for mild idiopathic mental retardation;Bundey, S.; Thake, A.; Todd, J.;J Med Genet,1989