@article{SF_1992__45_3_135196,
     author = {M. Petrich},
     title = {The semigroup generated  by certain operators  on the congruence lattice of a {Clifford} semigroup.},
     journal = {Semigroup forum},
     pages = {332--341},
     publisher = {mathdoc},
     volume = {45},
     number = {3},
     year = {1992},
     zbl = {0766.20021},
     url = {http://geodesic.mathdoc.fr/item/SF_1992__45_3_135196/}
}