TY  - JOUR
AU  - Yu. D. Burago
AU  - V. A. Toponogov
TI  - On three-dimensional Riemannian spaces with curvature bounded above
JO  - Matematičeskie zametki
PY  - 1973
SP  - 881
EP  - 887
VL  - 13
IS  - 6
PB  - mathdoc
UR  - http://geodesic.mathdoc.fr/item/MZM_1973_13_6_a9/
LA  - ru
ID  - MZM_1973_13_6_a9
ER  -