@article{MZ_1973__133_171960,
     author = {Johann Walter},
     title = {Regular {Eigenvalue} {Problems} with {Eigenvalue} {Parameter} in the {Boundary} {Condition.}},
     journal = {Mathematische Zeitschrift},
     pages = {301--312},
     publisher = {mathdoc},
     volume = {133},
     year = {1973},
     zbl = {0246.47058},
     url = {http://geodesic.mathdoc.fr/item/MZ_1973__133_171960/}
}