@article{GDZPPN001254189, title = {Subsemigroups of the finite complexes of a group.}, journal = {Semigroup forum}, volume = {20}, year = {1980}, pages = {285-292}, zbl = {0456.20035}, url = {http://dml.mathdoc.fr/item/GDZPPN001254189} }
Pedersen, F.P.; Sizer, W.S. Subsemigroups of the finite complexes of a group.. Semigroup forum, Tome 20 (1980) pp. 285-292. http://gdmltest.u-ga.fr/item/GDZPPN001254189/