@article{JRAM_1925__154_149564,
     author = {F. M\"uller},
     title = {Zur {Geometrie} der {Gruppe} aller {Ber\"uhrungstransformationen} der {Kugeln.}},
     journal = {Journal f\"ur die reine und angewandte Mathematik},
     pages = {131--142},
     publisher = {mathdoc},
     volume = {154},
     year = {1925},
     zbl = {51.0498.03},
     url = {http://geodesic.mathdoc.fr/item/JRAM_1925__154_149564/}
}