To cite rags2ridges in publications use:

Peeters CFW, Bilgrau AE, van Wieringen WN (2022). “rags2ridges: A One-Stop-$\ell_2$-Shop for Graphical Modeling of High-Dimensional Precision Matrices.” Journal of Statistical Software, 102(4), 1–32. doi:10.18637/jss.v102.i04.

Corresponding BibTeX entry:

  @Article{,
    title = {{rags2ridges}: A One-Stop-$\ell_2$-Shop for Graphical
      Modeling of High-Dimensional Precision Matrices},
    author = {Carel F. W. Peeters and Anders Ellern Bilgrau and Wessel
      N. {van Wieringen}},
    journal = {Journal of Statistical Software},
    year = {2022},
    volume = {102},
    number = {4},
    pages = {1--32},
    doi = {10.18637/jss.v102.i04},
  }