@article{1183741852,
author = {Howard, Paul E.},
title = {Subgroups of a Free Group and the Axiom of Choice},
journal = {J. Symbolic Logic},
volume = {50},
number = {1},
year = {1985},
pages = { 458-467},
language = {en},
url = {http://dml.mathdoc.fr/item/1183741852}
}
Howard, Paul E. Subgroups of a Free Group and the Axiom of Choice. J. Symbolic Logic, Tome 50 (1985) no. 1, pp. 458-467. http://gdmltest.u-ga.fr/item/1183741852/