@article{02123466, title = {The commutativity relation in the symmetric semigroup.}, journal = {Sibirskij Matematicheskij Zhurnal}, volume = {45}, year = {2004}, pages = {1130-1135}, zbl = {1058.20054}, language = {en}, url = {http://dml.mathdoc.fr/item/02123466} }
Kolmykov, V.A. The commutativity relation in the symmetric semigroup.. Sibirskij Matematicheskij Zhurnal, Tome 45 (2004) pp. 1130-1135. http://gdmltest.u-ga.fr/item/02123466/