@article{GDZPPN002067013,
title = {Two-knot groups with torsion free abelian normal subgroups of rank two.},
journal = {Commentarii mathematici Helvetici},
volume = {63},
year = {1988},
pages = {664-671},
zbl = {0666.57016},
url = {http://dml.mathdoc.fr/item/GDZPPN002067013}
}
Hillman, Jonathan A. Two-knot groups with torsion free abelian normal subgroups of rank two.. Commentarii mathematici Helvetici, Tome 63 (1988) pp. 664-671. http://gdmltest.u-ga.fr/item/GDZPPN002067013/