To cite multiPIM in publications use:

Stephan J. Ritter, Nicholas P. Jewell, Alan E. Hubbard (2014). R Package multiPIM: A Causal Inference Approach to Variable Importance Analysis. Journal of Statistical Software, 57(8), 1-29. URL http://www.jstatsoft.org/v57/i08/.

Corresponding BibTeX entry:

  @Article{,
    title = {{R} Package {multiPIM}: A Causal Inference Approach to
      Variable Importance Analysis},
    author = {Stephan J. Ritter and Nicholas P. Jewell and Alan E.
      Hubbard},
    journal = {Journal of Statistical Software},
    year = {2014},
    volume = {57},
    number = {8},
    pages = {1--29},
    url = {http://www.jstatsoft.org/v57/i08/},
  }