Voir la notice de l'article provenant de la source European Digital Mathematics Library
@article{SF_1978__16_134283, author = {W.R. Nico}, title = {The core congruence on a monoid.}, journal = {Semigroup forum}, pages = {141--146}, publisher = {mathdoc}, volume = {16}, year = {1978}, zbl = {0389.20055}, url = {http://geodesic.mathdoc.fr/item/SF_1978__16_134283/} }
W.R. Nico. The core congruence on a monoid.. Semigroup forum, Tome 16 (1978), pp. 141-146. http://geodesic.mathdoc.fr/item/SF_1978__16_134283/