%0 Journal Article
%A E. V. Radkevich
%T Hypoelliptic operators with multiple characteristics
%J Sbornik. Mathematics
%D 1969
%P 181-205
%V 8
%N 2
%I mathdoc
%U http://geodesic.mathdoc.fr/item/SM_1969_8_2_a3/
%G en
%F SM_1969_8_2_a3