@inproceedings{shing-tung1977remarks,
title={Remarks on the group of isometries of a Riemannian manifold},
author={Shing-Tung Yau},
url={http://archive.ymsc.tsinghua.edu.cn/pacm_paperurl/20191224204007590847115},
booktitle={Topology},
volume={16},
number={3},
pages={239-247},
year={1977},
}

Shing-Tung Yau. Remarks on the group of isometries of a Riemannian manifold. 1977. Vol. 16. In Topology. pp.239-247. http://archive.ymsc.tsinghua.edu.cn/pacm_paperurl/20191224204007590847115.