@inproceedings{r.1940the,
title={The existence of minimal surfaces of given topological structure under prescribed boundary conditions},
author={R. Courant},
url={http://archive.ymsc.tsinghua.edu.cn/pacm_paperurl/20170108203115800653616},
booktitle={Acta Mathematica},
volume={72},
number={1},
pages={51-98},
year={1940},
}
R. Courant. The existence of minimal surfaces of given topological structure under prescribed boundary conditions. 1940. Vol. 72. In Acta Mathematica. pp.51-98. http://archive.ymsc.tsinghua.edu.cn/pacm_paperurl/20170108203115800653616.