@article{1102976437,
author = {Kahn, Harold David},
title = {Covering semigroups.},
journal = {Pacific J. Math.},
volume = {35},
number = {3},
year = {1970},
pages = { 427-439},
language = {en},
url = {http://dml.mathdoc.fr/item/1102976437}
}
Kahn, Harold David. Covering semigroups.. Pacific J. Math., Tome 35 (1970) no. 3, pp. 427-439. http://gdmltest.u-ga.fr/item/1102976437/