TY  - JOUR
TI  - [unknown]
JO  - Acta mathematica Universitatis Comenianae
PY  - 1990
SP  - 11
EP  - 18
VL  - 56-57
PB  - mathdoc
UR  - http://geodesic.mathdoc.fr/item/AMUC_1990__56-57_186066/
ID  - AMUC_1990__56-57_186066
ER  -