@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://www.numdam.org/item/CM_1940__7__372_0/}
}