@article{MZ_1954__60_169426,
     author = {Herbert Knothe},
     title = {Eine kennzeichnende {Eigenschaft} der {Ellipse.}},
     journal = {Mathematische Zeitschrift},
     pages = {235--242},
     publisher = {mathdoc},
     volume = {60},
     year = {1954},
     zbl = {0055.39804},
     url = {http://geodesic.mathdoc.fr/item/MZ_1954__60_169426/}
}