@article{SF_1988__37_1_134932,
     author = {G. Thierrin and C.M. Reis and Y.Q. Guo},
     title = {Relatively f-disjunctive languages.},
     journal = {Semigroup forum},
     pages = {289--300},
     publisher = {mathdoc},
     volume = {37},
     number = {1},
     year = {1988},
     zbl = {0648.20064},
     url = {http://geodesic.mathdoc.fr/item/SF_1988__37_1_134932/}
}