@article{MOMA_1983__96_178144,
     author = {A. M\"uller-Rettkowski},
     title = {Existenz und {Eindeutigkeit} f\"ur {L\"osungen} des {Neumann-Tricomi-Problems} im ...},
     journal = {Monatshefte f\"ur Mathematik},
     pages = {143--156},
     publisher = {mathdoc},
     volume = {96},
     year = {1983},
     zbl = {0517.35064},
     url = {http://geodesic.mathdoc.fr/item/MOMA_1983__96_178144/}
}