@article{MZ_1922__13_167701,
     author = {J. H\"orn},
     title = {Zur {Theorie} der nichtlinearen {Differentialgleichungen}},
     journal = {Mathematische Zeitschrift},
     pages = {263--282},
     publisher = {mathdoc},
     volume = {13},
     year = {1922},
     zbl = {48.0501.01},
     url = {http://geodesic.mathdoc.fr/item/MZ_1922__13_167701/}
}