To cite panelr in publications use:

Long JA (2019). panelr: Regression Models and Utilities for Repeated Measures and Panel Data. R package version 0.7.0, https://cran.r-project.org/package=panelr.

Corresponding BibTeX entry:

  @Manual{panelr,
    title = {panelr: Regression Models and Utilities for Repeated
      Measures and Panel Data},
    author = {Jacob A. Long},
    year = {2019},
    note = {R package version 0.7.0},
    url = {https://cran.r-project.org/package=panelr},
  }