@inproceedings{alexander2007nonself-adjoint,
title={Nonself-adjoint operators with almost Hermitian spectrum: Cayley identity and some questions of spectral structure},
author={Alexander V. Kiselev, and Serguei Naboko},
url={http://archive.ymsc.tsinghua.edu.cn/pacm_paperurl/20170108203624054958949},
booktitle={Arkiv for Matematik},
volume={47},
number={1},
pages={91-125},
year={2007},
}

Alexander V. Kiselev, and Serguei Naboko. Nonself-adjoint operators with almost Hermitian spectrum: Cayley identity and some questions of spectral structure. 2007. Vol. 47. In Arkiv for Matematik. pp.91-125. http://archive.ymsc.tsinghua.edu.cn/pacm_paperurl/20170108203624054958949.