@inproceedings{d.1965curves,
title={Curves on 2-manifolds: A counterexample},
author={D. B. A. Epstein, and H. Zieschang},
url={http://archive.ymsc.tsinghua.edu.cn/pacm_paperurl/20170108203208039877006},
booktitle={Acta Mathematica},
volume={115},
number={1},
pages={109-110},
year={1965},
}