@article{GDZPPN001257935, title = {The minimal ideals of a multiplicative and additive subsemigroup of \ss N.}, journal = {Semigroup forum}, volume = {31}, year = {1985}, pages = {283-292}, zbl = {0576.22006}, url = {http://dml.mathdoc.fr/item/GDZPPN001257935} }
Hindman, N. The minimal ideals of a multiplicative and additive subsemigroup of ßN.. Semigroup forum, Tome 31 (1985) pp. 283-292. http://gdmltest.u-ga.fr/item/GDZPPN001257935/