title: [Physical efficiency of 9-year-old children in rural and urban populations].
mesh_terms: D000367:Age Factors; D002648:Child; D005260:Female; D006801:Humans; D008297:Male; D010809:Physical Fitness; D012424:Rural Population; D014505:Urban Population
vernacular_title: Wydolność fizyczna 9-letnich dzieci miejskich i wieskich