@article{MAN_1973__205_162489,
     author = {Dirk Ferus},
     title = {On {Isometrie} {Immersions} between {Hyperbolic} {Spaces.}},
     journal = {Mathematische Annalen},
     pages = {193--200},
     publisher = {mathdoc},
     volume = {205},
     year = {1973},
     zbl = {0245.53050},
     url = {http://geodesic.mathdoc.fr/item/MAN_1973__205_162489/}
}