@article{MZ_1976__146_172301,
     author = {Klaus Steffen},
     title = {On the {Existence} of {Surfaces} with {Prescribed} {Mean} {Curvature} and {Boundary.}},
     journal = {Mathematische Zeitschrift},
     pages = {113--136},
     publisher = {mathdoc},
     volume = {146},
     year = {1976},
     zbl = {0343.49016},
     url = {http://geodesic.mathdoc.fr/item/MZ_1976__146_172301/}
}