@inproceedings{sergiosuperconformal,
title={Superconformal Index, BPS Monodromy and Chiral Algebras},
author={Sergio Cecotti, Jaewon Song, Cumrun Vafa, and Wenbin Yan},
url={http://archive.ymsc.tsinghua.edu.cn/pacm_paperurl/20170208003248454030296},
}