@article{GDZPPN001250817, title = {Idempotent Endomorphisms on Standard Threads.}, journal = {Semigroup forum}, volume = {11}, year = {1975}, pages = {14-21}, zbl = {0299.20053}, url = {http://dml.mathdoc.fr/item/GDZPPN001250817} }
AKST, G.; Dence, T.P. Idempotent Endomorphisms on Standard Threads.. Semigroup forum, Tome 11 (1975) pp. 14-21. http://gdmltest.u-ga.fr/item/GDZPPN001250817/