@article{CMH_1982__57_139920,
     author = {R. Osserman and R. Schoen and D.A. Hoffman},
     title = {On the {Gauss} map of complete surfaces of constant mean curvature in {R3} and {R4.}},
     journal = {Commentarii mathematici Helvetici},
     pages = {519--531},
     publisher = {mathdoc},
     volume = {57},
     year = {1982},
     zbl = {0512.53008},
     url = {http://geodesic.mathdoc.fr/item/CMH_1982__57_139920/}
}