@inproceedings{juven2015field,
title={Field theory representation of gauge-gravity symmetry-protected topological invariants, group cohomology and beyond},
author={Juven Wang, Zheng-Cheng Gu, and Xiao-Gang Wen},
url={http://archive.ymsc.tsinghua.edu.cn/pacm_paperurl/20160831122502409232571},
booktitle={Phys. Rev. Lett.},
volume={114},
number={031601},
year={2015},
}

Juven Wang, Zheng-Cheng Gu, and Xiao-Gang Wen. Field theory representation of gauge-gravity symmetry-protected topological invariants, group cohomology and beyond. 2015. Vol. 114. In Phys. Rev. Lett.. http://archive.ymsc.tsinghua.edu.cn/pacm_paperurl/20160831122502409232571.