%0 Journal Article
%A V. V. Grushin
%T On a class of hypoelliptic operators
%J Sbornik. Mathematics
%D 1970
%P 458-476
%V 12
%N 3
%U http://geodesic.mathdoc.fr/item/SM_1970_12_3_a7/
%G en
%F SM_1970_12_3_a7