@article{SF_1971__3_133860,
     author = {L. O'Carroll},
     title = {A class of congruences on a posemigroup.},
     journal = {Semigroup forum},
     pages = {173--179},
     year = {1971},
     volume = {3},
     url = {http://geodesic.mathdoc.fr/item/SF_1971__3_133860/}
}