@misc{smirnov2019wolfenstein,
  title={The Wolfenstein potential for ultra-light mediators},
  author={Alexei Yu. Smirnov and Xun-Jie Xu},
  year={2019},
  eprint={1909.07505},
  archivePrefix={arXiv},
  primaryClass={hep-ph},
  url={https://arxiv.org/abs/1909.07505}
}