@article{GDZPPN001260081, title = {On open subsemigroups of connected groups.}, journal = {Semigroup forum}, volume = {38}, year = {1989}, pages = {347-362}, zbl = {0676.22001}, url = {http://dml.mathdoc.fr/item/GDZPPN001260081} }
Ruppert, W.A.F. On open subsemigroups of connected groups.. Semigroup forum, Tome 38 (1989) pp. 347-362. http://gdmltest.u-ga.fr/item/GDZPPN001260081/