@article{SF_1980__21_134442,
     author = {G. Thierrin and H. J\"urgensen},
     title = {Semigroups with each element disjunctive.},
     journal = {Semigroup forum},
     pages = {127--142},
     publisher = {mathdoc},
     volume = {21},
     year = {1980},
     zbl = {0454.20050},
     url = {http://geodesic.mathdoc.fr/item/SF_1980__21_134442/}
}