@article{MZ_1971__121_171547,
     author = {I.M.S. Dey and J. Cossey and S. Meskin},
     title = {Subgroups of {Knot} {Groups.}},
     journal = {Mathematische Zeitschrift},
     pages = {99--103},
     publisher = {mathdoc},
     volume = {121},
     year = {1971},
     zbl = {0222.55006},
     url = {http://geodesic.mathdoc.fr/item/MZ_1971__121_171547/}
}