@article{CMH_1993__68_2_140307,
     author = {Joel Hass and Peter Scott},
     title = {Homotopy and isotopy in dimension three.},
     journal = {Commentarii mathematici Helvetici},
     pages = {341--364},
     publisher = {mathdoc},
     volume = {68},
     number = {2},
     year = {1993},
     zbl = {0805.57008},
     url = {http://geodesic.mathdoc.fr/item/CMH_1993__68_2_140307/}
}