To cite package 'plot3logit' in publications use:

Santi F, Dickson M, Espa G, Giuliani D (2021). plot3logit: Ternary Plots for Trinomial Regression Models. R package version 3.1.0.

Corresponding BibTeX entry:

  @Manual{,
    title = {plot3logit: Ternary Plots for Trinomial Regression
      Models},
    author = {F. Santi and M. M. Dickson and G. Espa and D. Giuliani},
    year = {2021},
    note = {R package version 3.1.0},
  }