@article{GDZPPN001247506,
title = {Perfect monoids.},
journal = {Semigroup forum},
volume = {2},
year = {1971},
pages = {95-118},
language = {en},
url = {http://dml.mathdoc.fr/item/GDZPPN001247506}
}
Isbell, J.R. Perfect monoids.. Semigroup forum, Tome 2 (1971) pp. 95-118. http://gdmltest.u-ga.fr/item/GDZPPN001247506/