TY  - JOUR
TI  - [unknown]
JO  - Acta mathematica Universitatis Comenianae
PY  - 1981
SP  - 53
EP  - 62
VL  - 38
PB  - mathdoc
UR  - http://geodesic.mathdoc.fr/item/AMUC_1981__38_185802/
ID  - AMUC_1981__38_185802
ER  -