To cite the 'regspec' package in publications use:

Powell B, Nason G, Elliott D and Smith P (2016). Non-parametric Bayesian Spectrum Estimation for Multirate Data. R package version 2.4, https://CRAN.R-project.org/package=regspec.

Nason GP, Powell B, Elliott D and Smith P (2016). “Should we sample a time series more frequently? Decision support via multirate spectrum estimation.” Journal of the Royal Statistical Society, Series A, 179, pp. XXX–XXX. http://www.stats.bris.ac.uk/~guy.

Corresponding BibTeX entries:

  @Manual{,
    title = {Non-parametric Bayesian Spectrum Estimation for Multirate
      Data},
    author = {Ben Powell and Guy Nason and Duncan Elliott and Paul
      Smith},
    year = {2016},
    note = {R package version 2.4},
    url = {https://CRAN.R-project.org/package=regspec},
  }

  @Article{,
    title = {Should we sample a time series more frequently? Decision
      support via multirate spectrum estimation},
    author = {G. P. Nason and B. Powell and D. Elliott and P. Smith},
    journal = {Journal of the Royal Statistical Society, Series A},
    volume = {179},
    year = {2016},
    pages = {XXX--XXX},
    url = {http://www.stats.bris.ac.uk/~guy},
  }