%0 Journal Article
%A M. A. Grinfel'd
%T On the theory of ray method of the wave front investigation in nonlinear problems
%J Doklady Akademii Nauk
%D 1979
%P 337-340
%V 247
%N 2
%I mathdoc
%U http://geodesic.mathdoc.fr/item/DAN_1979_247_2_a19/
%G ru
%F DAN_1979_247_2_a19