@inproceedings{marston1947deformation,
title={Deformation classes of meromorphic functions and their extensions to interior transformations},
author={Marston Morse, and Maurice Heins},
url={http://archive.ymsc.tsinghua.edu.cn/pacm_paperurl/20170108203122760037670},
booktitle={Acta Mathematica},
volume={79},
number={1},
pages={51-103},
year={1947},
}
Marston Morse, and Maurice Heins. Deformation classes of meromorphic functions and their extensions to interior transformations. 1947. Vol. 79. In Acta Mathematica. pp.51-103. http://archive.ymsc.tsinghua.edu.cn/pacm_paperurl/20170108203122760037670.