@inproceedings{hans1941beweis,
title={Beweis einer Caratheodoryschen Vermutung},
author={Hans Ludwig Hamburger},
url={http://archive.ymsc.tsinghua.edu.cn/pacm_paperurl/20170108203116948635625},
booktitle={Acta Mathematica},
volume={73},
number={1},
pages={175-332},
year={1941},
}