@article{1250129189,
author = {Bittman, Richard M. and Levy, Lawrence S.},
title = {Idempotent Artinian rings and projective covers},
journal = {Rocky Mountain J. Math.},
volume = {9},
number = {4},
year = {1979},
pages = { 425-440},
language = {en},
url = {http://dml.mathdoc.fr/item/1250129189}
}
Bittman, Richard M.; Levy, Lawrence S. Idempotent Artinian rings and projective covers. Rocky Mountain J. Math., Tome 9 (1979) no. 4, pp. 425-440. http://gdmltest.u-ga.fr/item/1250129189/