To cite the 'quantspec' package in publications use:

Tobias Kley (2011). quantspec: Quantile-based Spectral Analysis Functions. R package version 0.2.
Dette, H., Hallin, M., Kley, T. & Volgushev, S. (2011) Of Copulas, Quantiles, Ranks and Spectra: an $L_1$-approach to spectral analysis. http://arxiv.org/abs/1111.7205

Corresponding BibTeX entries:

  @Manual{,
    title = {quantspec: Quantile-based Spectral Analysis Functions},
    author = {Tobias Kley},
    year = {2011},
    note = {R package version 0.2},
  }
  @Article{,
    title = {Of Copulas, Quantiles, Ranks and Spectra: an
      $L_1$-approach to spectral analysis},
    author = {Holger Dette and Marc Hallin and Tobias Kley and
      Stanislav Volgushev},
    journal = {arXiv},
    year = {2011},
    url = {http://arxiv.org/abs/1111.7205},
  }