title: [An epidemiologic investigation of mental retardation in two communes of Yexian County].
mesh_terms: D000293:Adolescent; D000328:Adult; D002648:Child; D002675:Child, Preschool; D002681:China; D005260:Female; D006801:Humans; D008607:Intellectual Disability / Q000453:epidemiology*; D008297:Male; D008403:Mass Screening; D008875:Middle Aged