To cite package 'fungible' in publications use:

Waller, N. G. & Jones, J. A. (2016). fungible: Fungible coefficients and Monte Carlo functions. R package version 1.5.

Corresponding BibTeX entry:

  @Manual{,
    title = {fungible: Fungible coefficients and Monte Carlo
      functions.},
    author = {Niels G. Waller and Jeff A. Jones},
    year = {2016},
    note = {version 1.5},
  }