%0 Journal Article %A I. P. Martynov %T Third-order systems without fixed critical points %J Differencialʹnye uravneniâ %D 1982 %P 792-804 %V 18 %N 5 %I mathdoc %U http://geodesic.mathdoc.fr/item/DE_1982_18_5_a9/ %G ru %F DE_1982_18_5_a9