@inproceedings{stefan1977mathematical,
title={Mathematical aspects of 't Hooft's eigenvalue problem in two-dimensional quantum chromodynamics},
author={Stefan Hildebrandt},
url={http://archive.ymsc.tsinghua.edu.cn/pacm_paperurl/20170108203504720049303},
booktitle={Arkiv for Matematik},
volume={17},
number={1},
pages={29-38},
year={1977},
}
Stefan Hildebrandt. Mathematical aspects of 't Hooft's eigenvalue problem in two-dimensional quantum chromodynamics. 1977. Vol. 17. In Arkiv for Matematik. pp.29-38. http://archive.ymsc.tsinghua.edu.cn/pacm_paperurl/20170108203504720049303.