TY  - JOUR
AU  - N. V. Efimov
TI  - Surfaces with a~slowly changing negative curvature
JO  - Trudy Matematicheskogo Instituta imeni V.A. Steklova
PY  - 1966
SP  - 1
EP  - 55
VL  - 21
IS  - 5
PB  - mathdoc
UR  - http://geodesic.mathdoc.fr/item/RM_1966_21_5_a0/
LA  - en
ID  - RM_1966_21_5_a0
ER  -