@article{MAN_1950__122_160207,
     author = {Frank L\"obell},
     title = {Zur {Frage} der {Vertauschbarkeit} geod\"atischer {Richtungsableitungen}},
     journal = {Mathematische Annalen},
     pages = {152--156},
     publisher = {mathdoc},
     volume = {122},
     year = {1950},
     zbl = {0037.38901},
     url = {http://geodesic.mathdoc.fr/item/MAN_1950__122_160207/}
}