To cite package ‘planex’ in publications use:

  Demarqui FN (2022). _planex: Planejamento e Análise de Experimentos_.
  R package version 0.1.5, <https://fndemarqui.github.io/planex/>.

A BibTeX entry for LaTeX users is

  @Manual{,
    title = {planex: Planejamento e Análise de Experimentos},
    author = {Fábio N. Demarqui},
    year = {2022},
    note = {R package version 0.1.5},
    url = {https://fndemarqui.github.io/planex/},
  }