[Near-sightedness and the length of school periods].
D000293:Adolescent; D002648:Child; D002940:Circadian Rhythm; D005260:Female; D006801:Humans; D008297:Male; D009216:Myopia / Q000209:etiology*; D012572:School Health Services; D012737:Sex Factors; D013997:Time Factors
Blizorukost' i dlitel'nost' uchebnykh zaniatii shkol'nikov.