@article{CMH_1930__2_138533,
     author = {Johann Jakob Burckhardt},
     title = {Bemerkungen zur arithmetischen {Berechnung} der {Bewegungsgruppen.}},
     journal = {Commentarii mathematici Helvetici},
     pages = {91--98},
     publisher = {mathdoc},
     volume = {2},
     year = {1930},
     zbl = {56.0867.01},
     url = {http://geodesic.mathdoc.fr/item/CMH_1930__2_138533/}
}