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