@article{GDZPPN001259776, title = {Centers of semigroup rings and conjugacy classes.}, journal = {Semigroup forum}, volume = {38}, year = {1989}, pages = {355-364}, zbl = {0655.16001}, url = {http://dml.mathdoc.fr/item/GDZPPN001259776} }
Dauns, John. Centers of semigroup rings and conjugacy classes.. Semigroup forum, Tome 38 (1989) pp. 355-364. http://gdmltest.u-ga.fr/item/GDZPPN001259776/