@inproceedings{yat2003superconformal,
title={Superconformal symmetry and hyperKhler manifolds with torsion},
author={Yat Sun Poon, and Andrew Swann},
url={http://archive.ymsc.tsinghua.edu.cn/pacm_paperurl/20191020221014759311343},
booktitle={Communications in mathematical physics},
volume={241},
number={1},
pages={177-189},
year={2003},
}

Yat Sun Poon, and Andrew Swann. Superconformal symmetry and hyperKhler manifolds with torsion. 2003. Vol. 241. In Communications in mathematical physics. pp.177-189. http://archive.ymsc.tsinghua.edu.cn/pacm_paperurl/20191020221014759311343.