To cite tvReg in publications use:

Casas I, Fernandez-Casal R (2018). tvReg: Time-Varying Coefficients Linear Regression for Single and Multiple Equations. R package version 0.3.0, https://CRAN.R-project.org/package=tvReg.

Corresponding BibTeX entry:

  @Manual{,
    title = {tvReg: Time-Varying Coefficients Linear Regression for
      Single and Multiple Equations},
    author = {Isabel Casas and Ruben Fernandez-Casal},
    year = {2018},
    note = {R package version 0.3.0},
    url = {https://CRAN.R-project.org/package=tvReg},
  }