%0 Journal Article
%A G. S. Rychkov
%T The maximal number of limit cycles of the system $\dot{y}=-x$, $\dot{x}=y-\sum_{i=0}^2a_i x^{2i+1}$ is equal to two
%J Differencialʹnye uravneniâ
%D 1975
%P 390-391
%V 11
%N 2
%I mathdoc
%U http://geodesic.mathdoc.fr/item/DE_1975_11_2_a23/
%G ru
%F DE_1975_11_2_a23