@inproceedings{alexander2003isoperimetric,
title={Isoperimetric properties of higher eigenvalues of elliptic operators},
author={Alexander Grigor'yan, and Shing-Tung Yau},
url={http://archive.ymsc.tsinghua.edu.cn/pacm_paperurl/20191224204210716305144},
booktitle={American Journal of Mathematics},
volume={125},
number={4},
pages={893-940},
year={2003},
}
Alexander Grigor'yan, and Shing-Tung Yau. Isoperimetric properties of higher eigenvalues of elliptic operators. 2003. Vol. 125. In American Journal of Mathematics. pp.893-940. http://archive.ymsc.tsinghua.edu.cn/pacm_paperurl/20191224204210716305144.