To cite DALEXtra in publications use:

Maksymiuk S, Biecek P (2020). DALEXtra: Extension for 'DALEX' Package. R package version 2.0.0, https://CRAN.R-project.org/package=DALEXtra.

Corresponding BibTeX entry:

  @Manual{,
    title = {DALEXtra: Extension for 'DALEX' Package},
    author = {Szymon Maksymiuk and Przemyslaw Biecek},
    year = {2020},
    url = {https://CRAN.R-project.org/package=DALEXtra},
    note = {R package version 2.0.0},
  }