@article{GDZPPN00124793X, title = {A class of congruences on a posemigroup.}, journal = {Semigroup forum}, volume = {2}, year = {1971}, pages = {173-179}, url = {http://dml.mathdoc.fr/item/GDZPPN00124793X} }
O'Carroll, L. A class of congruences on a posemigroup.. Semigroup forum, Tome 2 (1971) pp. 173-179. http://gdmltest.u-ga.fr/item/GDZPPN00124793X/