@inproceedings{m.1936über,
title={Über kombinatorische Topologie},
author={M. Dehn},
url={http://archive.ymsc.tsinghua.edu.cn/pacm_paperurl/20170108203108871579561},
booktitle={Acta Mathematica},
volume={67},
number={1},
pages={123-168},
year={1936},
}