@inproceedings{henrik1908les,
title={Les dérivées premiéres et secondes du potentiel},
author={Henrik Petrini},
url={http://archive.ymsc.tsinghua.edu.cn/pacm_paperurl/20170108203020559640186},
booktitle={Acta Mathematica},
volume={31},
number={1},
pages={127-332},
year={1908},
}