@article{JRAM_1919__149_149481,
     author = {Paul Epstein},
     title = {\"Uber {Elementarkettenbr\"uche,} lineare {Substitutionen} und indefinite bin\"are quadratische {Formen.} {I.}},
     journal = {Journal f\"ur die reine und angewandte Mathematik},
     pages = {57--88},
     year = {1919},
     volume = {149},
     zbl = {47.0208.02},
     url = {http://geodesic.mathdoc.fr/item/JRAM_1919__149_149481/}
}