%0 Journal Article
%A Yu. V. Egorov
%T A priori estimates for first order differential operators
%J Doklady Akademii Nauk
%D 1969
%P 507-508
%V 185
%N 3
%I mathdoc
%U http://geodesic.mathdoc.fr/item/DAN_1969_185_3_a3/
%G ru
%F DAN_1969_185_3_a3