%0 Journal Article
%A P. A. Frolov
%T Topological structure of normally solvable elliptic operators with constant coefficients in the plane
%J Doklady Akademii Nauk
%D 1970
%P 1238-1240
%V 191
%N 6
%I mathdoc
%U http://geodesic.mathdoc.fr/item/DAN_1970_191_6_a10/
%G ru
%F DAN_1970_191_6_a10