%0 Journal Article
%A V. V. Lychagin
%T Nonlinear differential equations and contact geometry
%J Doklady Akademii Nauk
%D 1978
%P 273-276
%V 238
%N 2
%I mathdoc
%U http://geodesic.mathdoc.fr/item/DAN_1978_238_2_a2/
%G ru
%F DAN_1978_238_2_a2