%0 Journal Article
%A V. V. Amel'kin
%T Isochrony in cases of a center and a structurally unstable focus
%J Differencialʹnye uravneniâ
%D 1982
%P 1073-1075
%V 18
%N 6
%I mathdoc
%U http://geodesic.mathdoc.fr/item/DE_1982_18_6_a18/
%G ru
%F DE_1982_18_6_a18