To cite RRreg in publications use:

Heck, D.W. & Moshagen, M. (2016). RRreg: Correlation and Regression Analyses for Randomized Response Data. R package version 0.6.1. https://CRAN.R-project.org/package=RRreg

Corresponding BibTeX entry:

  @Manual{,
    title = {RRreg: Correlation and Regression Analyses for Randomized
      Response Data},
    author = {Daniel W. Heck and Morten Moshagen},
    year = {2016},
    note = {R package version 0.6.1)},
    url = {https://CRAN.R-project.org/package=RRreg},
  }