%0 Journal Article
%A G. S. Rychkov
%T The uniqueness of the limit cycle of the system $\dot y=-g(x)$, $\dot x=-f(x)$
%J Differencialʹnye uravneniâ
%D 1969
%P 563-564
%V 5
%N 3
%I mathdoc
%U http://geodesic.mathdoc.fr/item/DE_1969_5_3_a17/
%G ru
%F DE_1969_5_3_a17