@article{MAN_1881__18_156969,
     author = {Klein},
     title = {Ueber {K\"orper,} welche von confocalen {Fl\"achen} zweiten {Grades} begrenzt sind},
     journal = {Mathematische Annalen},
     pages = {410--427},
     publisher = {mathdoc},
     volume = {18},
     year = {1881},
     zbl = {13.0728.01},
     url = {http://geodesic.mathdoc.fr/item/MAN_1881__18_156969/}
}