TY  - JOUR
TI  - [unknown]
JO  - Acta mathematica Universitatis Comenianae
PY  - 1989
SP  - 133
EP  - 140
VL  - 54-55
PB  - mathdoc
UR  - http://geodesic.mathdoc.fr/item/AMUC_1989__54-55_186026/
ID  - AMUC_1989__54-55_186026
ER  -