%0 Journal Article
%A Viktor Schroeder
%T Structure of flat subspaces in low-dimensional manilfolds of nonpositiv curvature.
%J Manuscripta mathematica
%D 1989
%P 77-106
%V 64
%N 2
%I mathdoc
%U http://geodesic.mathdoc.fr/item/MM2_1989__64_2_155397/
%F MM2_1989__64_2_155397