[Hygienic evaluation of difficulties of studies in an elementary school].
D002648:Child; D003479:Curriculum; D006801:Humans; D007858:Learning / Q000502:physiology*; D005222:Mental Fatigue / Q000175:diagnosis; D012572:School Health Services; D014586:USSR
Gigienicheskaia otsenka trudnosti urokov v nachal'noĭ shkole.