@inproceedings{pavel1976remark,
title={Remark on the decay of a mixed state},
author={Pavel Exner},
url={http://archive.ymsc.tsinghua.edu.cn/pacm_paperurl/20191020133523615873742},
booktitle={Czechoslovak Journal of Physics B},
volume={26},
number={9},
pages={976-982},
year={1976},
}