%0 Journal Article
%A L. A. Cherkas
%A A. A. Grin'
%T A second-degree polynomial Dulac function for a cubic system on the plane
%J Differencialʹnye uravneniâ
%D 1997
%P 1435-1436
%V 33
%N 10
%I mathdoc
%U http://geodesic.mathdoc.fr/item/DE_1997_33_10_a19/
%G ru
%F DE_1997_33_10_a19