%0 Journal Article %A I. Tazhimuratov %T Periodic solutions of a system of first-order partial differential equations %J Matematičeskie zametki %D 1981 %P 363-369 %V 30 %N 3 %I mathdoc %U http://geodesic.mathdoc.fr/item/MZM_1981_30_3_a4/ %G ru %F MZM_1981_30_3_a4