%0 Journal Article
%A B. Tilson
%T The intersection of free submonoids of a free monoid is free.
%J Semigroup forum
%D 1972
%P 345-350
%V 4
%I mathdoc
%U http://geodesic.mathdoc.fr/item/SF_1972__4_133915/
%F SF_1972__4_133915