%0 Journal Article
%A A. A. Tolstonogov
%T A~theorem of existence of an optimal control for the Goursat--Darboux problem without convexity assumptions
%J Izvestiya. Mathematics 
%D 2000
%P 807-826
%V 64
%N 4
%I mathdoc
%U http://geodesic.mathdoc.fr/item/IM2_2000_64_4_a5/
%G en
%F IM2_2000_64_4_a5