@inproceedings{pavel2005spectrum,
title={Spectrum of the Schrdinger operator in a perturbed periodically twisted tube},
author={Pavel Exner, and Hynek Kovak},
url={http://archive.ymsc.tsinghua.edu.cn/pacm_paperurl/20191020125637820884620},
booktitle={Letters in Mathematical Physics},
volume={73},
number={3},
pages={183-192},
year={2005},
}

Pavel Exner, and Hynek Kovak. Spectrum of the Schrdinger operator in a perturbed periodically twisted tube. 2005. Vol. 73. In Letters in Mathematical Physics. pp.183-192. http://archive.ymsc.tsinghua.edu.cn/pacm_paperurl/20191020125637820884620.