@article{GDZPPN001249576,
title = {Semigroups with periodic properties.},
journal = {Semigroup forum},
volume = {7},
year = {1974},
pages = {292-309},
zbl = {0275.22007},
url = {http://dml.mathdoc.fr/item/GDZPPN001249576}
}
Day, Jane M. Semigroups with periodic properties.. Semigroup forum, Tome 7 (1974) pp. 292-309. http://gdmltest.u-ga.fr/item/GDZPPN001249576/