To cite package ‘extremis’ in publications use:

de Carvalho M, Rubio R, Palacios V (2021). extremis: Statistics of Extremes. R package version 1.21, https://github.com/extremestats/extremis.

Corresponding BibTeX entry:

  @Manual{,
    title = {extremis: Statistics of Extremes},
    author = {Miguel {de Carvalho} and Rodrigo Rubio and Vianey
      Palacios},
    year = {2021},
    note = {R package version 1.21},
    url = {https://github.com/extremestats/extremis},
  }