@article{MAN_1987__279_3_164322,
     author = {Reinhard Mennicken and Manfred M\"oller},
     title = {Equivalence of {Boundary} {Eigenvalue} {Operator} {Fuctions} and their {Characteristic} {Matrix} {Functions.}},
     journal = {Mathematische Annalen},
     pages = {267--276},
     publisher = {mathdoc},
     volume = {279},
     number = {3},
     year = {1987},
     zbl = {0613.47011},
     url = {http://geodesic.mathdoc.fr/item/MAN_1987__279_3_164322/}
}