@article{AM2_1978__18_136802,
     author = {Martin Schechter},
     title = {Wave operators for pairs of spaces and the {Klein-Gordon} equation. {(Short} {Communication).}},
     journal = {Aequationes mathematicae},
     pages = {398--399},
     publisher = {mathdoc},
     volume = {18},
     year = {1978},
     url = {http://geodesic.mathdoc.fr/item/AM2_1978__18_136802/}
}