%0 Journal Article %A K. Urbanik %T A counterexample on generalized convolutions %J Colloquium Mathematicum %D 1987 %P 143-147 %V 54 %N 1 %I mathdoc %U http://geodesic.mathdoc.fr/articles/10.4064/cm-54-1-143-147/ %R 10.4064/cm-54-1-143-147 %G en %F 10_4064_cm_54_1_143_147