@article{1029000641,
author = {Hill, Paul},
title = {The covering theorem for upper basic subgroups.},
journal = {Michigan Math. J.},
volume = {18},
number = {1},
year = {1971},
pages = { 187-192},
language = {en},
url = {http://dml.mathdoc.fr/item/1029000641}
}
Hill, Paul. The covering theorem for upper basic subgroups.. Michigan Math. J., Tome 18 (1971) no. 1, pp. 187-192. http://gdmltest.u-ga.fr/item/1029000641/