@inproceedings{beifang2001graph,
title={Graph homotopy and Graham homotopy},
author={Beifang Chen, Shing-Tung Yau, and Yeong-Nan Yeh},
url={http://archive.ymsc.tsinghua.edu.cn/pacm_paperurl/20191224203815466139088},
booktitle={Discrete Mathematics},
volume={241},
pages={153-170},
year={2001},
}
Beifang Chen, Shing-Tung Yau, and Yeong-Nan Yeh. Graph homotopy and Graham homotopy. 2001. Vol. 241. In Discrete Mathematics. pp.153-170. http://archive.ymsc.tsinghua.edu.cn/pacm_paperurl/20191224203815466139088.