title: An epidemiological study on mental retardation among children in Chang-qiao area of Beijing.
mesh_terms: D000293:Adolescent; D002648:Child; D002675:Child, Preschool; D002681:China; D005260:Female; D006801:Humans; D008607:Intellectual Disability / Q000453:epidemiology* / Q000517:prevention & control; D008297:Male; D008403:Mass Screening