To cite package ‘rotations’ in publications use:

  Bryan Stafill, Heike Hofmann, Ulrike Genschel (2014). rotations: An R
  package for SO(3) data. The R Journal, 6(1):68-78. URL
  https://journal.r-project.org/archive/2014-1/stanfill-hofmann-genschel.pdf.

A BibTeX entry for LaTeX users is

  @Article{,
    title = {rotations: An R package for SO(3) Data},
    author = {Bryan Stanfill and Heike Hofmann and Ulrike Genschel},
    journal = {The R Journal},
    year = {2014},
    volume = {6},
    issue = {1},
    pages = {68-78},
    url = {https://journal.r-project.org/archive/2014-1/stanfill-hofmann-genschel.pdf},
  }