@article{CMH_1985__60_140034,
     author = {John F. Hughes and Paul M. Melvin},
     title = {The {Smale} invariant of a knot.},
     journal = {Commentarii mathematici Helvetici},
     pages = {615--627},
     publisher = {mathdoc},
     volume = {60},
     year = {1985},
     zbl = {0586.57017},
     url = {http://geodesic.mathdoc.fr/item/CMH_1985__60_140034/}
}