To cite package ‘interflex’ in publications use:

  Jens Hainmueller, Jonathan Mummolo, Yiqing Xu, Ziyi Liu (2021).
  _interflex: Multiplicative Interaction Models Diagnostics and
  Visualization_. R package version 1.2.6,
  <https://CRAN.R-project.org/package=interflex>.

A BibTeX entry for LaTeX users is

  @Manual{,
    title = {interflex: Multiplicative Interaction Models Diagnostics and Visualization},
    author = {{Jens Hainmueller} and {Jonathan Mummolo} and {Yiqing Xu} and {Ziyi Liu}},
    year = {2021},
    note = {R package version 1.2.6},
    url = {https://CRAN.R-project.org/package=interflex},
  }