TY  - JOUR
AU  - B. A. Efimov
AU  - G. I. Chertanov
TI  - On some operations on classes of topological spaces
JO  - Doklady Akademii Nauk
PY  - 1974
SP  - 25
EP  - 27
VL  - 216
IS  - 1
PB  - mathdoc
UR  - http://geodesic.mathdoc.fr/item/DAN_1974_216_1_a4/
LA  - ru
ID  - DAN_1974_216_1_a4
ER  -