%0 Journal Article
%A A. P. Sadovskii
%T The conditions for the center of a certain system of differential equations
%J Differencialʹnye uravneniâ
%D 1971
%P 2285-2286
%V 7
%N 12
%I mathdoc
%U http://geodesic.mathdoc.fr/item/DE_1971_7_12_a23/
%G ru
%F DE_1971_7_12_a23