@article{MZ_1981__177_173072,
     author = {Roman Boutellier},
     title = {Curvature and {Functions} with {Bounded} {Boundary} {Rotation.}},
     journal = {Mathematische Zeitschrift},
     pages = {395--400},
     publisher = {mathdoc},
     volume = {177},
     year = {1981},
     zbl = {0442.30010},
     url = {http://geodesic.mathdoc.fr/item/MZ_1981__177_173072/}
}