@article{GDZPPN00126396X, title = {Monoids over which all regular left acts are flat.}, journal = {Semigroup forum}, volume = {51}, year = {1995}, pages = {135-140}, zbl = {0827.20078}, url = {http://dml.mathdoc.fr/item/GDZPPN00126396X} }
Liu, Z. Monoids over which all regular left acts are flat.. Semigroup forum, Tome 51 (1995) pp. 135-140. http://gdmltest.u-ga.fr/item/GDZPPN00126396X/