[Hygienic characteristics of the instruction of elementary school children in a 5-day school week].
D002648:Child; D002657:Child Development; D004493:Education / Q000639:trends*; D006801:Humans; D014586:USSR
Gigienicheskaia kharakteristika obucheniia deteĭ mladshego shkol'nogo vozrasta pri 5-dnevnoĭ uchebnoĭ nedele.