%0 Journal Article
%A A. P. Vorob'ev
%T Qualitative investigation in the large of integral curves of isochronous systems of two differential equations
%J Differencialʹnye uravneniâ
%D 1965
%P 439-441
%V 1
%N 4
%I mathdoc
%U http://geodesic.mathdoc.fr/item/DE_1965_1_4_a1/
%G ru
%F DE_1965_1_4_a1