TY  - JOUR
AU  - Santos, J. C. 
TI  - When is a group homomorphism a covering homomorphism? 
JO  - Extracta mathematicae
PY  - 2007
SP  - 325
EP  - 330
VL  - 22
IS  - 3
PB  - mathdoc
UR  - http://geodesic.mathdoc.fr/item/EXMATH_2007_2007_1_a22/
LA  - en
ID  - EXMATH_2007_2007_1_a22
ER  -