To cite package ‘metasplines’ in publications use:

  Tommi Härkänen, Heli Tapanainen, Laura Sares-Jäske, Satu Männistö,
  Niina E. Kaartinen, Laura Paalanen (2025). “Novel pooling method for
  nonlinear cohort analysis and meta-analysis estimates: Predicting
  health outcomes based on climate-friendly diets.” Under revision.

A BibTeX entry for LaTeX users is

  @Unpublished{,
    title = {Novel pooling method for nonlinear cohort analysis and meta-analysis estimates: Predicting health outcomes based on climate-friendly diets},
    author = {{Tommi Härkänen} and {Heli Tapanainen} and {Laura Sares-Jäske} and {Satu Männistö} and {Niina E. Kaartinen} and {Laura Paalanen}},
    year = {2025},
    note = {Under revision},
  }