@inproceedings{charles1972a,
title={A proof of a conjecture of Loewner and of the conjecture of caratheodory on umbilic points},
author={Charles J. Titus},
url={http://archive.ymsc.tsinghua.edu.cn/pacm_paperurl/20170108203229226730153},
booktitle={Acta Mathematica},
volume={131},
number={1},
pages={43-77},
year={1972},
}
Charles J. Titus. A proof of a conjecture of Loewner and of the conjecture of caratheodory on umbilic points. 1972. Vol. 131. In Acta Mathematica. pp.43-77. http://archive.ymsc.tsinghua.edu.cn/pacm_paperurl/20170108203229226730153.