To cite ggpie in publications use:

Song Y (2022). ggpie: Create Pie, Donut and Rose Pie Plot with 'ggplot2'.. R package version 0.2.2, https://CRAN.R-project.org/package=ggpie.

Corresponding BibTeX entry:

  @Manual{,
    title = {ggpie: Create Pie, Donut and Rose Pie Plot with
      'ggplot2'.},
    author = {Yabing Song},
    note = {R package version 0.2.2},
    year = {2022},
    url = {https://CRAN.R-project.org/package=ggpie},
  }