@article{GDZPPN001256505, title = {Permutable duo semigroups.}, journal = {Semigroup forum}, volume = {30}, year = {1984}, pages = {155-172}, zbl = {0524.20040}, url = {http://dml.mathdoc.fr/item/GDZPPN001256505} }
Varisco, A.; Cherubini, A. Permutable duo semigroups.. Semigroup forum, Tome 30 (1984) pp. 155-172. http://gdmltest.u-ga.fr/item/GDZPPN001256505/