@misc{AMUC_1991__58-59_186085,
     title = {[unknown]},
     journal = {Acta mathematica Universitatis Comenianae},
     pages = {247--258},
     year = {1991},
     volume = {58-59},
     url = {http://geodesic.mathdoc.fr/item/AMUC_1991__58-59_186085/}
}