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@article{CM_1937__4__235_0, author = {Freudenthal, Hans}, title = {Bettische {Gruppe} mod. 1 und {Hopfsche} {Gruppe}}, journal = {Compositio Mathematica}, pages = {235--238}, publisher = {Johnson Reprint Corporation}, volume = {4}, year = {1937}, zbl = {0016.28102}, language = {de}, url = {http://geodesic.mathdoc.fr/item/CM_1937__4__235_0/} }
Freudenthal, Hans. Bettische Gruppe mod. 1 und Hopfsche Gruppe. Compositio Mathematica, Tome 4 (1937), pp. 235-238. http://geodesic.mathdoc.fr/item/CM_1937__4__235_0/