@inproceedings{lai2001a,
title={A Lower Bound for the Number of Edges in a Graph Containing No Two Cycles of the Same Length},
author={Lai Chunhui},
url={http://archive.ymsc.tsinghua.edu.cn/pacm_paperurl/20161227085453346694694},
booktitle={ Electronic Journal of Combinatorics},
volume={8},
year={2001},
}

Lai Chunhui. A Lower Bound for the Number of Edges in a Graph Containing No Two Cycles of the Same Length. 2001. Vol. 8. In Electronic Journal of Combinatorics. http://archive.ymsc.tsinghua.edu.cn/pacm_paperurl/20161227085453346694694.