@article{GDZPPN001260774, title = {Arithmetical semigroups defined by congruences.}, journal = {Semigroup forum}, volume = {43}, year = {1991}, pages = {59-62}, zbl = {0734.20027}, url = {http://dml.mathdoc.fr/item/GDZPPN001260774} }
Halter-Koch, F. Arithmetical semigroups defined by congruences.. Semigroup forum, Tome 43 (1991) pp. 59-62. http://gdmltest.u-ga.fr/item/GDZPPN001260774/