To cite package ‘splines2’ in publications use:

  Wang W, Yan J (2025). _splines2: Regression Spline Functions and
  Classes_. R package version 0.5.5.9000,
  <https://CRAN.R-project.org/package=splines2>.

A BibTeX entry for LaTeX users is

  @Manual{splines2-package,
    title = {{splines2}: {R}egression Spline Functions and Classes},
    author = {Wenjie Wang and Jun Yan},
    year = {2025},
    url = {https://CRAN.R-project.org/package=splines2},
    note = {R package version 0.5.5.9000},
  }

  Wang W, Yan J (2021). “Shape-Restricted Regression Splines with R
  Package splines2.” _Journal of Data Science_, *19*(3), 498-517.
  doi:10.6339/21-JDS1020 <https://doi.org/10.6339/21-JDS1020>.

A BibTeX entry for LaTeX users is

  @Article{splines2-paper,
    title = {Shape-Restricted Regression Splines with {R} Package {splines2}},
    author = {Wenjie Wang and Jun Yan},
    journal = {Journal of Data Science},
    year = {2021},
    volume = {19},
    number = {3},
    pages = {498--517},
    doi = {10.6339/21-JDS1020},
  }