@inproceedings{jonatan2005riemannian,
title={Riemannian geometry on the diffeomorphism group of the circle},
author={Jonatan Lenells},
url={http://archive.ymsc.tsinghua.edu.cn/pacm_paperurl/20170108203620519465920},
booktitle={Arkiv for Matematik},
volume={45},
number={2},
pages={297-325},
year={2005},
}

Jonatan Lenells. Riemannian geometry on the diffeomorphism group of the circle. 2005. Vol. 45. In Arkiv for Matematik. pp.297-325. http://archive.ymsc.tsinghua.edu.cn/pacm_paperurl/20170108203620519465920.