@article{SF_1992__44_1_135155,
     author = {B. Billhardt},
     title = {On inverse semigroups the closure of whose set of idempotents is a {Clifford} semigroup.},
     journal = {Semigroup forum},
     pages = {320--331},
     publisher = {mathdoc},
     volume = {44},
     number = {1},
     year = {1992},
     zbl = {0747.20032},
     url = {http://geodesic.mathdoc.fr/item/SF_1992__44_1_135155/}
}