1. . Internationl Statistical Classification of Disease and Related Health Problems. Tenth Revision. (1992) Geneva World Health Organization.
2. American Psychiatric Association. (1994) Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition. Washington, DC, American Psychiatric Association.
3. Brown SW (2003) Towards definitions: Learning disability, mental handicap and intelligence. In Trimble MR (ed) Learning disability and epilepsy: An integrative approach. Clarius Press, London, pp. 1-16.
4. Beange OH, Taplin JE. (1996) Prevalence of intellectual disability in northern Sydney adults. J Intellect Disabil Res 40: 191-7.
5. Bhasin TK, Brocksen S, Avchen RN et al. (2006) Prevalence of four developmental disabilities among children aged 8 years — Metropolitan Atlanta Developmental Disabilities Surveillance Program, 1996 and 2000. MMWR — Morbidity & Mortality Weekly Report. 55 (SS-1):1-9.