TY  - JOUR
TI  - [unknown]
JO  - Acta mathematica Universitatis Comenianae
PY  - 1980
SP  - 109
EP  - 120
VL  - 37
PB  - mathdoc
UR  - http://geodesic.mathdoc.fr/item/AMUC_1980__37_185787/
ID  - AMUC_1980__37_185787
ER  -