@article{MM2_1976__19_154413,
     author = {J\"urgen T\"olke},
     title = {Zum {Integrationsproblem} sph\"arischer {H\"ullkurvenpaare.}},
     journal = {Manuscripta mathematica},
     pages = {189--194},
     publisher = {mathdoc},
     volume = {19},
     year = {1976},
     zbl = {0334.53002},
     url = {http://geodesic.mathdoc.fr/item/MM2_1976__19_154413/}
}