TY  - JOUR
AU  - L. É. Reiziņš
TI  - On the number of characteristic directions
JO  - Trudy Matematicheskogo Instituta imeni V.A. Steklova
PY  - 1964
VL  - 19
IS  - 5
PB  - mathdoc
UR  - http://geodesic.mathdoc.fr/item/RM_1964_19_5_a7/
LA  - ru
ID  - RM_1964_19_5_a7
ER  -