@inproceedings{satoko2009flat,
title={FLAT SURFACES WITH SINGULARITIES IN EUCLIDEAN 3-SPACE},
author={Satoko Murata, and Masaaki Umehara},
url={http://archive.ymsc.tsinghua.edu.cn/pacm_paperurl/20160911183528926695775},
booktitle={Journal of Differential Geometry},
volume={82},
number={2},
pages={279-316},
year={2009},
}

Satoko Murata, and Masaaki Umehara. FLAT SURFACES WITH SINGULARITIES IN EUCLIDEAN 3-SPACE. 2009. Vol. 82. In Journal of Differential Geometry. pp.279-316. http://archive.ymsc.tsinghua.edu.cn/pacm_paperurl/20160911183528926695775.