To cite the cordillera package in publications use:

Rusch, Thomas and Mair, Patrick and Hornik, Kurt (2017). Assessing and quantifying clusteredness: The OPTICS Cordillera. Journal of Computational and Graphical Statistics.

Corresponding BibTeX entry:

  @Article{,
    author = {Thomas Rusch and Patrick Mair and Kurt Hornik},
    title = {Assessing and quantifying clusteredness: The {OPTICS}
      {C}ordillera},
    journal = {Journal of Computational and Graphical Statistics},
    number = {1},
    volume = {1},
    pages = {9-9},
    year = {2017},
    url = {http://dx.doi.org/10.1080/10618600.2017.1349664},
    doi = {10.1080/10618600.2017.1349664},
  }