@article{GDZPPN001256432, title = {Monoids on the 2-disk.}, journal = {Semigroup forum}, volume = {30}, year = {1984}, pages = {83-92}, zbl = {0531.22001}, url = {http://dml.mathdoc.fr/item/GDZPPN001256432} }
Castellano, B.M. Monoids on the 2-disk.. Semigroup forum, Tome 30 (1984) pp. 83-92. http://gdmltest.u-ga.fr/item/GDZPPN001256432/