To cite package ‘DIFplus’ in publications use:

Dai S, French B, Finch W, Iverson A (2020). DIFplus: Multilevel Mantel-Haenszel Statistics for Differential Item Functioning Detection. R package version 1.1, https://CRAN.R-project.org/package=DIFplus.

Corresponding BibTeX entry:

  @Manual{,
    title = {DIFplus: Multilevel Mantel-Haenszel Statistics for
      Differential Item Functioning Detection},
    author = {Shenghai Dai and Brian F. French and W. Holmes Finch and
      Andrew Iverson},
    year = {2020},
    note = {R package version 1.1},
    url = {https://CRAN.R-project.org/package=DIFplus},
  }