To cite package ‘NISTunits’ in publications use:

Gama J (2016). NISTunits: Fundamental Physical Constants and Unit Conversions from NIST. R package version 1.0.1, https://CRAN.R-project.org/package=NISTunits.

Corresponding BibTeX entry:

  @Manual{,
    title = {NISTunits: Fundamental Physical Constants and Unit
      Conversions from NIST},
    author = {Jose Gama},
    year = {2016},
    note = {R package version 1.0.1},
    url = {https://CRAN.R-project.org/package=NISTunits},
  }