@article{CMH_1969__44_139394,
     author = {J. Levine},
     title = {Knot {Cobordism} {Groups} in {Codimension} {Two.}},
     journal = {Commentarii mathematici Helvetici},
     pages = {229--244},
     publisher = {mathdoc},
     volume = {44},
     year = {1969},
     zbl = {0176.22101},
     url = {http://geodesic.mathdoc.fr/item/CMH_1969__44_139394/}
}