%0 Journal Article
%A I. I. Pleshkan
%T Conditions for the isochronism of systems of two differential equations
%J Differencialʹnye uravneniâ
%D 1968
%P 1991-1993
%V 4
%N 11
%I mathdoc
%U http://geodesic.mathdoc.fr/item/DE_1968_4_11_a6/
%G ru
%F DE_1968_4_11_a6