@article{GDZPPN001260871,
title = {Closure of singly generated subsemigroups of S.},
journal = {Semigroup forum},
volume = {43},
year = {1991},
pages = {147-154},
zbl = {0721.22001},
url = {http://dml.mathdoc.fr/item/GDZPPN001260871}
}
Hindman, N.; Pym, J. Closure of singly generated subsemigroups of S.. Semigroup forum, Tome 43 (1991) pp. 147-154. http://gdmltest.u-ga.fr/item/GDZPPN001260871/