To cite package ‘genie’ in publications use:

  Gagolewski M., Bartoszuk M., Cena A. Genie: A new, fast, and
  outlier-resistant hierarchical clustering algorithm. Information
  Sciences 363, 2016, pp. 8-23, doi:10.1016/j.ins.2016.05.003.

A BibTeX entry for LaTeX users is

  @Article{,
    title = {{Genie}: {A} new, fast, and outlier-resistant hierarchical clustering algorithm},
    author = {Marek Gagolewski and Maciej Bartoszuk and Anna Cena},
    journal = {Information Sciences},
    year = {2016},
    volume = {363},
    pages = {8--23},
    doi = {10.1016/j.ins.2016.05.003},
  }