To cite package ‘clustree’ in publications use:

  Zappia L, Oshlack A. Clustering trees: a visualization for evaluating
  clusterings at multiple resolutions. Gigascience. 2018;7.
  DOI:gigascience/giy083

A BibTeX entry for LaTeX users is

  @Article{,
    author = {Luke Zappia and Alicia Oshlack},
    title = {Clustering trees: a visualization for evaluating clusterings at
             multiple resolutions},
    journal = {GigaScience},
    volume = {7},
    number = {7},
    month = {jul},
    year = {2018},
    url = {https://doi.org/10.1093/gigascience/giy083},
    doi = {10.1093/gigascience/giy083},
  }