TY  - JOUR
AU  - I. M. Krichever
TI  - Obstructions to the existence of $S^1$-actions. Bordism of ramified coverings
JO  - Izvestiya. Mathematics 
PY  - 1976
SP  - 783
EP  - 797
VL  - 10
IS  - 4
PB  - mathdoc
UR  - http://geodesic.mathdoc.fr/item/IM2_1976_10_4_a6/
LA  - en
ID  - IM2_1976_10_4_a6
ER  -