@article{GDZPPN001258834, title = {Bicharacters of semigroups.}, journal = {Semigroup forum}, volume = {33}, year = {1986}, pages = {253-264}, zbl = {0625.20055}, url = {http://dml.mathdoc.fr/item/GDZPPN001258834} }
Lesokhin, M.M.; Popyrin, A. V. Bicharacters of semigroups.. Semigroup forum, Tome 33 (1986) pp. 253-264. http://gdmltest.u-ga.fr/item/GDZPPN001258834/