@Article{,
  title = {Difference-in-differences with multiple time periods},
  author = {Brantly Callaway and Pedro H.C. Sant'Anna},
  year = {2020},
  journal = {Forthcoming at the Journal of Econometrics},
  url = {https://arxiv.org/abs/1803.09015},
}

@Misc{,
  title = {did: Difference in Differences},
  author = {Brantly Callaway and Pedro H.C. Sant'Anna},
  year = {2020},
  note = {R package version 2.0.1.908},
  url = {https://bcallaway11.github.io/did/},
}