@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/