@inproceedings{norman1978a,
title={A cutting and pasting of noncompact polygons with applications to fuchsian groups},
author={Norman Purzitsky},
url={http://archive.ymsc.tsinghua.edu.cn/pacm_paperurl/20170108203250470584267},
booktitle={Acta Mathematica},
volume={143},
number={1},
pages={233-250},
year={1978},
}
Norman Purzitsky. A cutting and pasting of noncompact polygons with applications to fuchsian groups. 1978. Vol. 143. In Acta Mathematica. pp.233-250. http://archive.ymsc.tsinghua.edu.cn/pacm_paperurl/20170108203250470584267.