@article{SF_1984__29_134675,
     author = {P.M. Higgins},
     title = {Epimorphisms, permutation identities and finite semigroups.},
     journal = {Semigroup forum},
     pages = {87--98},
     publisher = {mathdoc},
     volume = {29},
     year = {1984},
     zbl = {0546.20051},
     url = {http://geodesic.mathdoc.fr/item/SF_1984__29_134675/}
}