@article{GDZPPN001264001, title = {Periodic endomorphisms of a free monoid.}, journal = {Semigroup forum}, volume = {51}, year = {1995}, pages = {193-204}, zbl = {0833.20072}, url = {http://dml.mathdoc.fr/item/GDZPPN001264001} }
Reis, C.M. Periodic endomorphisms of a free monoid.. Semigroup forum, Tome 51 (1995) pp. 193-204. http://gdmltest.u-ga.fr/item/GDZPPN001264001/