To cite did2s in publications use:

Butts & Gardner, "The R Journal: did2s: Two-Stage Difference-in-Differences", The R Journal, 2022

Corresponding BibTeX entry:

  @Manual{,
    title = {did2s: Two-Stage Difference-in-Differences Following
      Gardner (2021)},
    author = {Kyle Butts and John Gardner},
    year = {2021},
    url = {https://journal.r-project.org/articles/RJ-2022-048/},
  }