TY  - JOUR
AU  - R. M. Geidel'man
TI  - Projective classification of ruled surfaces, and focal transforms of a~surface
JO  - Izvestiâ vysših učebnyh zavedenij. Matematika
PY  - 1974
SP  - 51
EP  - 53
IS  - 12
PB  - mathdoc
UR  - http://geodesic.mathdoc.fr/item/IVM_1974_12_a6/
LA  - ru
ID  - IVM_1974_12_a6
ER  -