To cite package ‘npiv’ in publications use:

  Racine J, Christensen T (2025). _npiv: Nonparametric Instrumental
  Variables Estimation and Inference_. R package version 0.1.3,
  <https://CRAN.R-project.org/package=npiv>.

A BibTeX entry for LaTeX users is

  @Manual{,
    title = {npiv: Nonparametric Instrumental Variables Estimation and Inference},
    author = {Jeffrey S. Racine and Timothy Christensen},
    year = {2025},
    note = {R package version 0.1.3},
    url = {https://CRAN.R-project.org/package=npiv},
  }