@article{MOMA_1974__78_186321,
     author = {Werner Kratz},
     title = {Zur {Unl\"osbarkeit} linearer partieller {Differentialgleichungen.}},
     journal = {Monatshefte f\"ur Mathematik},
     pages = {223--228},
     publisher = {mathdoc},
     volume = {78},
     year = {1974},
     zbl = {0288.35007},
     url = {http://geodesic.mathdoc.fr/item/MOMA_1974__78_186321/}
}