@article{SF_1984__29_134681,
     author = {J. Karhum\"aki},
     title = {A note on intersections of free submonoids of a free monoid.},
     journal = {Semigroup forum},
     pages = {183--206},
     publisher = {mathdoc},
     volume = {29},
     year = {1984},
     zbl = {0555.20037},
     url = {http://geodesic.mathdoc.fr/item/SF_1984__29_134681/}
}