%0 Journal Article
%A A. P. Sadovskii
%T Solution of the center and focus problem for a cubic system of nonlinear oscillations
%J Differencialʹnye uravneniâ
%D 1997
%P 236-244
%V 33
%N 2
%I mathdoc
%U http://geodesic.mathdoc.fr/item/DE_1997_33_2_a12/
%G ru
%F DE_1997_33_2_a12