@inproceedings{david1920gaston,
title={Gaston Darboux},
author={David Hilbert},
url={http://archive.ymsc.tsinghua.edu.cn/pacm_paperurl/20170108203035032485300},
booktitle={Acta Mathematica},
volume={42},
number={1},
pages={269-273},
year={1920},
}