@article{CMH_1992__67_3_140273,
     author = {J. Scott Carter},
     title = {Extending immersed circles in the sphere to immersed disks in the ball.},
     journal = {Commentarii mathematici Helvetici},
     pages = {337--348},
     publisher = {mathdoc},
     volume = {67},
     number = {3},
     year = {1992},
     zbl = {0766.57018},
     url = {http://geodesic.mathdoc.fr/item/CMH_1992__67_3_140273/}
}