To cite package ‘etree’ in publications use:

Giubilei R, Padellini T, Brutti P (2022). etree: Classification and Regression with Structured and Mixed-Type Data. R package version 0.1.0, https://github.com/ricgbl/etree.

Corresponding BibTeX entry:

  @Manual{,
    title = {etree: Classification and Regression with Structured and
      Mixed-Type Data},
    author = {Riccardo Giubilei and Tullia Padellini and Pierpaolo
      Brutti},
    year = {2022},
    note = {R package version 0.1.0},
    url = {https://github.com/ricgbl/etree},
  }