To cite package ‘doubt’ in publications use:

Fabri A (2020). doubt: Enable Operators Containing the '?' Symbol. R package version 0.1.0, https://github.com/moodymudskipper/doubt.

Corresponding BibTeX entry:

  @Manual{,
    title = {doubt: Enable Operators Containing the '?' Symbol},
    author = {Antoine Fabri},
    year = {2020},
    note = {R package version 0.1.0},
    url = {https://github.com/moodymudskipper/doubt},
  }