To cite the 'quantspec' package in publications use:

Kley, T. (2015). quantspec: Quantile-based Spectral Analysis Functions. R package version 1.2-0.

Corresponding BibTeX entry:

  @Manual{,
    title = {quantspec: Quantile-based Spectral Analysis Functions},
    author = {Tobias Kley},
    year = {2015},
    note = {R package version 1.2-0},
  }