%0 Journal Article
%A Marek Kuczma
%T On a theorem of B. Barna.
%J Aequationes mathematicae
%D 1980
%P 173-178
%V 21
%I mathdoc
%U http://geodesic.mathdoc.fr/item/AM2_1980__21_182428/
%F AM2_1980__21_182428