TY  - JOUR
AU  - B. Tilson
TI  - The intersection of free submonoids of a free monoid is free.
JO  - Semigroup forum
PY  - 1972
SP  - 345
EP  - 350
VL  - 4
PB  - mathdoc
UR  - http://geodesic.mathdoc.fr/item/SF_1972__4_133915/
ID  - SF_1972__4_133915
ER  -