%0 Journal Article
%A E. I. Ganzha
%T Hypoellipticity of a second-order differential operator with quadratic form of variable sign
%J Trudy Matematicheskogo Instituta imeni V.A. Steklova
%D 1986
%P 175-176
%V 41
%N 4
%I mathdoc
%U http://geodesic.mathdoc.fr/item/RM_1986_41_4_a5/
%G en
%F RM_1986_41_4_a5