@article{SF_1980__21_134440,
     author = {J. Crawley},
     title = {Epimorphisms and semilattices of semigroups.},
     journal = {Semigroup forum},
     pages = {95--112},
     publisher = {mathdoc},
     volume = {21},
     year = {1980},
     zbl = {0446.22003},
     url = {http://geodesic.mathdoc.fr/item/SF_1980__21_134440/}
}