@inproceedings{feng2008angle,
title={Angle structures and normal surfaces},
author={Feng Luo, and Stephan Tillmann},
url={http://archive.ymsc.tsinghua.edu.cn/pacm_paperurl/20191224205819412249351},
booktitle={Transactions of the American Mathematical Society},
volume={360},
number={6},
pages={2849-2866},
year={2008},
}
Feng Luo, and Stephan Tillmann. Angle structures and normal surfaces. 2008. Vol. 360. In Transactions of the American Mathematical Society. pp.2849-2866. http://archive.ymsc.tsinghua.edu.cn/pacm_paperurl/20191224205819412249351.