Please cite both the liureg related paper and the lmridge package:

Imdad, M. U. & Aslam, M. (2018). lmridge: Linear Ridge Regression with Ridge Penalty and Ridge Statistics. URL https://CRAN.R-project.org/package=lmridge, R package version 1.2

Corresponding BibTeX entry:

  @Manual{,
    title = {{lmridge}: Linear Ridge Regression with Ridge Penalty and
      Ridge Statistics},
    author = {M. U. Imdad and M. Aslam},
    year = {2018},
    note = {R package version 1.2},
    url = {https://CRAN.R-project.org/package=lmridge},
  }