@article{MAN_1981__255_182825,
     author = {W.D. Evans},
     title = {On the {Spectra} of {Schr\"odinger} {Operators} with a {Complex} {Potential.}},
     journal = {Mathematische Annalen},
     pages = {57--76},
     publisher = {mathdoc},
     volume = {255},
     year = {1981},
     zbl = {0438.35025},
     url = {http://geodesic.mathdoc.fr/item/MAN_1981__255_182825/}
}