To cite package ‘ftsspec’ in publications use:

  Tavakoli S (2026). _ftsspec: Spectral Density Estimation and
  Comparison for Functional Time Series_. R package version 1.0.1,
  <https://github.com/stavakol/ftsspec>.

A BibTeX entry for LaTeX users is

  @Manual{,
    title = {ftsspec: Spectral Density Estimation and Comparison for Functional Time
Series},
    author = {Shahin Tavakoli},
    year = {2026},
    note = {R package version 1.0.1},
    url = {https://github.com/stavakol/ftsspec},
  }