@article{GDZPPN001249681, title = {Semigroups for which every S-system has the natural partial order.}, journal = {Semigroup forum}, volume = {7}, year = {1974}, pages = {51-55}, zbl = {0284.20064}, url = {http://dml.mathdoc.fr/item/GDZPPN001249681} }
McMorris, F.R.; Johnson, C.S. jr. Semigroups for which every S-system has the natural partial order.. Semigroup forum, Tome 7 (1974) pp. 51-55. http://gdmltest.u-ga.fr/item/GDZPPN001249681/