To cite package gvcm.cat in publications use:

Oelker, M.-R. (2015). gvcm.cat: Regularized Categorical Effects/Categorical Effect Modifiers/Continuous/Smooth Effects in GLMs. R package version 1.9.

Corresponding BibTeX entry:

  @Manual{,
    title = {{gvcm.cat}: Regularized Categorical Effects/Categorical
      Effect Modifiers/Continuous/Smooth Effects in GLMs},
    author = {Margret-Ruth Oelker},
    year = {2015},
    note = {R package version 1.9},
  }