@inproceedings{felix2005an,
title={An integral spectral representation of the propagator for the wave equation in the Kerr geometry},
author={Felix Finster, Niky Kamran, Joel Smoller, and Shing-Tung Yau},
url={http://archive.ymsc.tsinghua.edu.cn/pacm_paperurl/20191224204117163365134},
booktitle={Communications in mathematical physics},
volume={260},
number={2},
pages={257-298},
year={2005},
}

Felix Finster, Niky Kamran, Joel Smoller, and Shing-Tung Yau. An integral spectral representation of the propagator for the wave equation in the Kerr geometry. 2005. Vol. 260. In Communications in mathematical physics. pp.257-298. http://archive.ymsc.tsinghua.edu.cn/pacm_paperurl/20191224204117163365134.