To cite package ‘PPtreeregViz’ in publications use:

  Lee E, Cho H (2022). _PPtreeregViz: Projection Pursuit Regression
  Tree Visualization_. R package version 2.0.5,
  <https://CRAN.R-project.org/package=PPtreeregViz>.

A BibTeX entry for LaTeX users is

  @Manual{,
    title = {PPtreeregViz: Projection Pursuit Regression Tree Visualization},
    author = {Eun-Kyung Lee and HyunSun Cho},
    year = {2022},
    note = {R package version 2.0.5},
    url = {https://CRAN.R-project.org/package=PPtreeregViz},
  }