@article{GDZPPN001257919,
title = {The characterisation of monoids by properties of their S-systems.},
journal = {Semigroup forum},
volume = {31},
year = {1985},
pages = {251-266},
zbl = {0571.20067},
url = {http://dml.mathdoc.fr/item/GDZPPN001257919}
}
Gould, V. The characterisation of monoids by properties of their S-systems.. Semigroup forum, Tome 31 (1985) pp. 251-266. http://gdmltest.u-ga.fr/item/GDZPPN001257919/