%0 Journal Article
%A Udo Simon
%T On differential operators of second order on Riemannian manifolds with nonpositive curvature
%J Colloquium Mathematicum
%D 1974
%P 223-229
%V 31
%N 2
%I mathdoc
%U http://geodesic.mathdoc.fr/articles/10.4064/cm-31-2-223-229/
%R 10.4064/cm-31-2-223-229
%G en
%F 10_4064_cm_31_2_223_229