@article{GDZPPN001262289,
title = {Some closure properties in monoids.},
journal = {Semigroup forum},
volume = {46},
year = {1993},
pages = {73-77},
zbl = {0776.20022},
url = {http://dml.mathdoc.fr/item/GDZPPN001262289}
}
Schanuel, S.; Isbell, J. Some closure properties in monoids.. Semigroup forum, Tome 46 (1993) pp. 73-77. http://gdmltest.u-ga.fr/item/GDZPPN001262289/