@inproceedings{gustav1891sur,
title={Sur un problème de représentation conforme},
author={Gustav Cassel},
url={http://archive.ymsc.tsinghua.edu.cn/pacm_paperurl/20170108202952795553953},
booktitle={Acta Mathematica},
volume={15},
number={1},
pages={33-44},
year={1891},
}