@article{JRAM_1909__136_149313,
     author = {E. Hellinger},
     title = {Neue {Begr\"undung} der {Theorie} quadratischer {Formen} von unendlichvielen {Ver\"anderlichen.}},
     journal = {Journal f\"ur die reine und angewandte Mathematik},
     pages = {210--271},
     publisher = {mathdoc},
     volume = {136},
     year = {1909},
     zbl = {40.0393.01},
     url = {http://geodesic.mathdoc.fr/item/JRAM_1909__136_149313/}
}