To cite package ‘qfa’ in publications use:

Li T (2026). qfa: Quantile-Frequency Analysis (QFA) of Time Series and Spline Quantile Regression (SQR). R package version 5.0, https://CRAN.R-project.org/package=qfa.

Corresponding BibTeX entry:

  @Manual{,
    title = {qfa: Quantile-Frequency Analysis (QFA) of Time Series and
      Spline Quantile Regression (SQR)},
    author = {Ta-Hsin Li},
    year = {2026},
    note = {R package version 5.0},
    url = {https://CRAN.R-project.org/package=qfa},
  }