@inproceedings{nikolay2018on,
title={On the structure of band edges of 2-dimensional periodic elliptic operators},
author={Nikolay Filonov, and Ilya Kachkovskiy},
url={http://archive.ymsc.tsinghua.edu.cn/pacm_paperurl/20191128112914683656536},
booktitle={Acta Mathematica},
volume={221},
number={1},
pages={59 – 80},
year={2018},
}
Nikolay Filonov, and Ilya Kachkovskiy. On the structure of band edges of 2-dimensional periodic elliptic operators. 2018. Vol. 221. In Acta Mathematica. pp.59 – 80. http://archive.ymsc.tsinghua.edu.cn/pacm_paperurl/20191128112914683656536.