TY  - JOUR
AU  - V. V. Ryzhkov
TI  - Characteristic directions of a point mapping of $P_m$ into $P_n$
JO  - Itogi Nauki i Tekhniki. Seriya Problemy Geometrii. Trudy Geometricheskogo Seminara
PY  - 1971
SP  - 235
EP  - 242
VL  - 3
UR  - http://geodesic.mathdoc.fr/item/INTG_1971_3_a10/
LA  - ru
ID  - INTG_1971_3_a10
ER  -