@article{SF_1975__10_134100,
     author = {T.E. Hays},
     title = {Compact normal bands of groups.},
     journal = {Semigroup forum},
     pages = {67--75},
     year = {1975},
     volume = {10},
     zbl = {0303.22001},
     url = {http://geodesic.mathdoc.fr/item/SF_1975__10_134100/}
}