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@article{CM_1940__7__372_0, author = {Sidon, S.}, title = {\"Uber {Orthogonalsysteme}}, journal = {Compositio Mathematica}, pages = {372--375}, publisher = {Johnson Reprint Corporation}, volume = {7}, year = {1940}, mrnumber = {1995}, zbl = {0023.02503}, language = {de}, url = {http://geodesic.mathdoc.fr/item/CM_1940__7__372_0/} }
Sidon, S. Über Orthogonalsysteme. Compositio Mathematica, Tome 7 (1940), pp. 372-375. http://geodesic.mathdoc.fr/item/CM_1940__7__372_0/