@article{MZ_1958__69_169747,
     author = {G.L. Krabbe},
     title = {Convolution {Operators} which are not of {Scalar} {Type.}},
     journal = {Mathematische Zeitschrift},
     pages = {346--350},
     publisher = {mathdoc},
     volume = {69},
     year = {1958},
     zbl = {0080.10001},
     url = {http://geodesic.mathdoc.fr/item/MZ_1958__69_169747/}
}