@article{MZ_1923__16_174957,
     author = {P. Funk},
     title = {\"Uber {Fl\"achen} mit einem festen {Abstand} der konjugierten {Punkte} .},
     journal = {Mathematische Zeitschrift},
     pages = {159--162},
     year = {1923},
     volume = {16},
     zbl = {49.0510.01},
     url = {http://geodesic.mathdoc.fr/item/MZ_1923__16_174957/}
}