%0 Journal Article
%T [unknown]
%J Acta mathematica Universitatis Comenianae
%D 1987
%P 211-214
%V 48-49
%I mathdoc
%U http://geodesic.mathdoc.fr/item/AMUC_1987__48-49_185943/
%F AMUC_1987__48-49_185943