To cite vip in publications use:

Brandon M. Greenwell and Bradley C. Boehmke (2020). Variable Importance Plots—An Introduction to the vip Package. The R Journal, 12(1), 343--366. URL https://doi.org/10.32614/RJ-2020-013.

Corresponding BibTeX entry:

  @Article{,
    title = {Variable Importance Plots---An Introduction to the vip
      Package},
    author = {Brandon M. Greenwell and Bradley C. Boehmke},
    journal = {The R Journal},
    year = {2020},
    volume = {12},
    number = {1},
    pages = {343--366},
    url = {https://doi.org/10.32614/RJ-2020-013},
  }