To cite PPtreeViz in publications use:

Lee E (2018). “PPtreeViz: An R Package for Visualizing Projection Pursuit Classification Trees.” Journal of Statistical Software, 83(8), 1–30. doi:10.18637/jss.v083.i08.

Corresponding BibTeX entry:

  @Article{,
    title = {{PPtreeViz}: An {R} Package for Visualizing Projection
      Pursuit Classification Trees},
    author = {Eun-Kyung Lee},
    journal = {Journal of Statistical Software},
    year = {2018},
    volume = {83},
    number = {8},
    pages = {1--30},
    doi = {10.18637/jss.v083.i08},
  }