%0 Journal Article
%A A.A. Markov
%T On finitely generated subsemigroups of a free semigroup.
%J Semigroup forum
%D 1971
%P 251-258
%V 3
%I mathdoc
%U http://geodesic.mathdoc.fr/item/SF_1971__3_133864/
%F SF_1971__3_133864