@article{GDZPPN002486407, title = {The Foliation of Semigroups by Congruence Classes.}, journal = {Monatshefte f\"ur Mathematik}, volume = {105}, year = {1988}, pages = {179-204}, zbl = {0671.22003}, url = {http://dml.mathdoc.fr/item/GDZPPN002486407} }
Hofmann, K.H.; Ruppert, W.A.F. The Foliation of Semigroups by Congruence Classes.. Monatshefte für Mathematik, Tome 105 (1988) pp. 179-204. http://gdmltest.u-ga.fr/item/GDZPPN002486407/