To cite the SGP package in publications use:

  Damian W. Betebenner, Adam R. Van Iwaarden, Benjamin Domingue and Yi
  Shang (2024). SGP: Student Growth Percentiles & Percentile Growth
  Trajectories. (R package version 2.2-0.0) URL: https://sgp.io

A BibTeX entry for LaTeX users is

  @Manual{,
    title = {{SGP}: Student Growth Percentiles \& Percentile Growth Trajectories.},
    author = {Damian W. Betebenner and Adam R. {Van Iwaarden} and Benjamin Domingue and Yi Shang},
    year = {2024},
    note = {R package version 2.2-0.0},
    url = {https://sgp.io},
  }