To cite package 'plot3logit' in publications use:

Santi F, Dickson M, Espa G (2019). plot3logit: Ternary Plots for Trinomial Regression Models. R package version 1.0.2.

Corresponding BibTeX entry:

  @Manual{,
    title = {plot3logit: Ternary Plots for Trinomial Regression
      Models},
    author = {F. Santi and M. M. Dickson and G. Espa},
    year = {2019},
    note = {R package version 1.0.2},
  }