@article{GDZPPN001263153,
title = {Permutation functions and (n,m)-commutativity of semigroups .},
journal = {Semigroup forum},
volume = {48},
year = {1994},
pages = {71-78},
zbl = {0805.20051},
url = {http://dml.mathdoc.fr/item/GDZPPN001263153}
}
Nagy, A. Permutation functions and (n,m)-commutativity of semigroups .. Semigroup forum, Tome 48 (1994) pp. 71-78. http://gdmltest.u-ga.fr/item/GDZPPN001263153/