To cite panelr in publications use:

  Long JA (2020). _panelr: Regression Models and Utilities for Repeated
  Measures and Panel Data_. R package version 0.7.3,
  <https://cran.r-project.org/package=panelr>.

A BibTeX entry for LaTeX users is

  @Manual{panelr,
    title = {panelr: Regression Models and Utilities for Repeated Measures and Panel Data},
    author = {Jacob A. Long},
    year = {2020},
    note = {R package version 0.7.3},
    url = {https://cran.r-project.org/package=panelr},
  }