%0 Journal Article
%A Rainer Felix
%T Differential operators of the first order with degenerate principal symbols
%J Banach Center Publications
%D 1992
%P 147-161
%V 27
%N 1
%I mathdoc
%U http://geodesic.mathdoc.fr/articles/10.4064/-27-1-147-161/
%R 10.4064/-27-1-147-161
%G en
%F 10_4064__27_1_147_161