@article{2976,
author = {Haimo, Franklin},
title = {Free subgroups in the endomorphism ring of an Abelian free group},
journal = {Portugaliae mathematica},
volume = {40},
year = {1981},
pages = {393-398},
zbl = {0581.20024},
mrnumber = {0836100},
language = {en},
url = {http://dml.mathdoc.fr/item/2976}
}
Haimo, Franklin. Free subgroups in the endomorphism ring of an Abelian free group. Portugaliae mathematica, Tome 40 (1981) pp. 393-398. http://gdmltest.u-ga.fr/item/2976/