@article{SF_1974__6_133995,
     author = {J.B. Kirn},
     title = {No semigroup is a finite union of mutants.},
     journal = {Semigroup forum},
     pages = {360--361},
     publisher = {mathdoc},
     volume = {6},
     year = {1974},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/SF_1974__6_133995/}
}