@article{MAN_1987__277_164245,
     author = {Hubert Kalf and Rainer Hempel and Andreas M. Hinz},
     title = {On the {Essential} {Spectrum} of {Schr\"odinger} {Operators} with {Spherically} {Symmetric} {Potentials.}},
     journal = {Mathematische Annalen},
     pages = {197--208},
     publisher = {mathdoc},
     volume = {277},
     year = {1987},
     zbl = {0629.35028},
     url = {http://geodesic.mathdoc.fr/item/MAN_1987__277_164245/}
}