[A survey of myopia among middle and primary school pupils in Xining (author's transl)].
D000293:Adolescent; D000367:Age Factors; D002648:Child; D002675:Child, Preschool; D002681:China; D005260:Female; D006306:Health Surveys; D006801:Humans; D008297:Male; D009216:Myopia / Q000453:epidemiology* / Q000209:etiology