%0 Journal Article
%A L. Satko
%A O. Grosek
%T A new notion in the theory of semigroups.
%J Semigroup forum
%D 1980
%P 233-240
%V 20
%I mathdoc
%U http://geodesic.mathdoc.fr/item/SF_1980__20_134417/
%F SF_1980__20_134417