@article{GDZPPN001255622,
title = {Graph Monoids.},
journal = {Semigroup forum},
volume = {24},
year = {1982},
pages = {1-8},
zbl = {0497.05060},
url = {http://dml.mathdoc.fr/item/GDZPPN001255622}
}
Roush, F.W.; Kim, K.H.; Makar-Limanov, L.G. Graph Monoids.. Semigroup forum, Tome 24 (1982) pp. 1-8. http://gdmltest.u-ga.fr/item/GDZPPN001255622/