@article{MZ_1930__32_168252,
     author = {A., Wintner},
     title = {\"Uber die v. {Haerdtlsche} {Bahn}},
     journal = {Mathematische Zeitschrift},
     pages = {668--678},
     publisher = {mathdoc},
     volume = {32},
     year = {1930},
     zbl = {56.0778.04},
     url = {http://geodesic.mathdoc.fr/item/MZ_1930__32_168252/}
}