TY  - JOUR
TI  - [unknown]
JO  - Acta mathematica Universitatis Comenianae
PY  - 1989
SP  - 207
EP  - 210
VL  - 54-55
PB  - mathdoc
UR  - http://geodesic.mathdoc.fr/item/AMUC_1989__54-55_186034/
ID  - AMUC_1989__54-55_186034
ER  -