@article{GDZPPN002403390, title = {Homomorphisms and Duality for Torsion-free Groups.}, journal = {Mathematische Zeitschrift}, volume = {105}, year = {1968}, pages = {189-200}, zbl = {0169.03602}, url = {http://dml.mathdoc.fr/item/GDZPPN002403390} }
Warfield, R.B., Jr. Homomorphisms and Duality for Torsion-free Groups.. Mathematische Zeitschrift, Tome 105 (1968) pp. 189-200. http://gdmltest.u-ga.fr/item/GDZPPN002403390/