@article{aruna rao2020efficacy,
  title={The Efficacy of Botulinum Toxin in Cluster Headache:  A Systematic Review},
  author={brin freund,ivan s. kotchetkov,aruna rao},
  journal={Journal of Oral & Facial Pain and Headache},
  volume={34},
  number={2},
  pages={129--134},
  doi = {10.11607/ofph.2444},
  year={2020}
}