%0 Journal Article
%A N. I. Vulpe
%T Affine-invariant conditions for topological distinction of quadratic systems in the presence of a center
%J Differencialʹnye uravneniâ
%D 1983
%P 371-379
%V 19
%N 3
%I mathdoc
%U http://geodesic.mathdoc.fr/item/DE_1983_19_3_a0/
%G ru
%F DE_1983_19_3_a0