@article{GDZPPN001248308, title = {Clan acts and codimension.}, journal = {Semigroup forum}, volume = {4}, year = {1972}, pages = {206-214}, zbl = {0255.54032}, url = {http://dml.mathdoc.fr/item/GDZPPN001248308} }
Hofmann, K.H.; Day, J.M. Clan acts and codimension.. Semigroup forum, Tome 4 (1972) pp. 206-214. http://gdmltest.u-ga.fr/item/GDZPPN001248308/