@article{MZ_1957__67_169651,
     author = {Wolfgang Walter},
     title = {Verallgemeinerte {Laplace-Operatoren} und {Potentiale.}},
     journal = {Mathematische Zeitschrift},
     pages = {38--48},
     publisher = {mathdoc},
     volume = {67},
     year = {1957},
     zbl = {0078.09202},
     url = {http://geodesic.mathdoc.fr/item/MZ_1957__67_169651/}
}