TY  - JOUR
AU  - S. V. Buyalo
TI  - Euclidean planes in open three-dimensional manifolds of nonpositive curvature
JO  - Algebra i analiz
PY  - 1991
SP  - 102
EP  - 117
VL  - 3
IS  - 1
PB  - mathdoc
UR  - http://geodesic.mathdoc.fr/item/AA_1991_3_1_a3/
LA  - ru
ID  - AA_1991_3_1_a3
ER  -