TY  - JOUR
AU  - Viktor Schroeder
TI  - Structure of flat subspaces in low-dimensional manilfolds of nonpositiv curvature.
JO  - Manuscripta mathematica
PY  - 1989
SP  - 77
EP  - 106
VL  - 64
IS  - 2
PB  - mathdoc
UR  - http://geodesic.mathdoc.fr/item/MM2_1989__64_2_155397/
ID  - MM2_1989__64_2_155397
ER  -