@article{SF_1987__36_134892,
     author = {C.M. Reis},
     title = {A note on f-disjunctive languages.},
     journal = {Semigroup forum},
     pages = {159--166},
     year = {1987},
     volume = {36},
     zbl = {0627.20043},
     url = {http://geodesic.mathdoc.fr/item/SF_1987__36_134892/}
}