@article{MZ_1960__73_169846,
     author = {Wolfgang Walter},
     title = {\"Uber die {Differentialgleichung} u...= f(x, y, u, u..., u...). {III.} {Die} nichtcharakteristische {Anfangswertaufgabe.}},
     journal = {Mathematische Zeitschrift},
     pages = {268--279},
     publisher = {mathdoc},
     volume = {73},
     year = {1960},
     zbl = {0091.09202},
     url = {http://geodesic.mathdoc.fr/item/MZ_1960__73_169846/}
}