To cite package ‘ubiquity’ in publications use:

  Harrold, J.M., Abraham, A.K. Ubiquity: a framework for
  physiological/mechanism-based pharmacokinetic/pharmacodynamic model
  development and deployment. J Pharmacokinet Pharmacodyn 41, 141–151
  (2014). https://doi.org/10.1007/s10928-014-9352-6

A BibTeX entry for LaTeX users is

  @Article{,
    title = {Ubiquity: a framework for physiological/mechanism-based pharmacokinetic/pharmacodynamic model development and deployment},
    author = {J.M. Harrold and A.K. Abraham},
    journal = {Journal of Pharmacokinetics and Pharmacodynamics},
    year = {2014},
    volume = {41},
    number = {2},
    pages = {141-151},
    url = {https://doi.org/10.1007/s10928-014-9352-6},
  }