To cite package ‘RSpincalc’ in publications use:

  Gama J, Fuller J, Leva P (2015). _RSpincalc: Conversion Between
  Attitude Representations of DCM, Euler Angles, Quaternions, and Euler
  Vectors_. R package version 1.0.2,
  <https://CRAN.R-project.org/package=RSpincalc>.

A BibTeX entry for LaTeX users is

  @Manual{,
    title = {RSpincalc: Conversion Between Attitude Representations of DCM, Euler
Angles, Quaternions, and Euler Vectors},
    author = {Jose Gama and John Fuller and Paolo Leva},
    year = {2015},
    note = {R package version 1.0.2},
    url = {https://CRAN.R-project.org/package=RSpincalc},
  }