To cite karel in publications use:

  Prunello M (2024). karel: Learning programming with Karel the robot.
  R package version 0.1.1.9000, <https://mpru.github.io/karel/>.

A BibTeX entry for LaTeX users is

  @Misc{karelpackage,
    title = {karel: Learning programming with Karel the robot},
    author = {Marcos Prunello},
    year = {2024},
    url = {https://mpru.github.io/karel/},
  }