%0 Journal Article
%A S. Z. Levendorskii
%T On~the symbols of degenerate elliptic differential and hypoelliptic pseudodifferential operators
%J Izvestiya. Mathematics 
%D 1989
%P 543-561
%V 32
%N 3
%I mathdoc
%U http://geodesic.mathdoc.fr/item/IM2_1989_32_3_a4/
%G en
%F IM2_1989_32_3_a4