title: National and international studies in mental retardation.
mesh_terms: D000293:Adolescent; D002648:Child; D002675:Child, Preschool; D004812:Epidemiologic Methods; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008607:Intellectual Disability / Q000175:diagnosis / Q000453:epidemiology; D007390:International Agencies; D007391:International Cooperation; D008605:Mental Health Services; D010661:Phenylketonurias; D012106:Research; D012109:Research Support as Topic; D012936:Social Medicine; D009626:Terminology as Topic; D014944:World Health Organization