%0 Journal Article %A A. B. Vasil'eva %T On the theory of periodic solutions of partial differential equations with small parameters %J Differencialʹnye uravneniâ %D 1982 %P 889-892 %V 18 %N 5 %I mathdoc %U http://geodesic.mathdoc.fr/item/DE_1982_18_5_a21/ %G ru %F DE_1982_18_5_a21