@article{JRAM_1879__88_148440,
     author = {Rudolf Sturm},
     title = {Zur {Theorie} der {Fl\"achen} dritter {Ordnung.}},
     journal = {Journal f\"ur die reine und angewandte Mathematik},
     pages = {213--240},
     publisher = {mathdoc},
     volume = {88},
     year = {1879},
     zbl = {11.0447.01},
     url = {http://geodesic.mathdoc.fr/item/JRAM_1879__88_148440/}
}