@article{CMH_1934__6_138615,
     author = {J.J. Burckhardt},
     title = {Zur {Theorie} der {Bewegungsgruppen.}},
     journal = {Commentarii mathematici Helvetici},
     pages = {159--184},
     publisher = {mathdoc},
     volume = {6},
     year = {1934},
     language = {de},
     url = {http://geodesic.mathdoc.fr/item/CMH_1934__6_138615/}
}