%0 Journal Article
%A F. I. Karpelevich
%T Non-negative eigenfunctions of the Beltrami--Laplace operator on symmetric spaces of non-positive curvature
%J Doklady Akademii Nauk
%D 1963
%P 1274-1276
%V 151
%N 6
%I mathdoc
%U http://geodesic.mathdoc.fr/item/DAN_1963_151_6_a8/
%G ru
%F DAN_1963_151_6_a8