@article{MOMA_1983__95_178122,
     author = {Werner Ricker},
     title = {A {Criterion} for an {Operator} with {Real} {Spectrum} to {Be} of {Scalar-type.}},
     journal = {Monatshefte f\"ur Mathematik},
     pages = {229--234},
     publisher = {mathdoc},
     volume = {95},
     year = {1983},
     zbl = {0507.47020},
     url = {http://geodesic.mathdoc.fr/item/MOMA_1983__95_178122/}
}