To cite countreg in publications use:

  Zeileis A, Kleiber C (2024). _countreg: Count Data Regression_. R
  package version 0.3-0,
  <https://R-Forge.R-project.org/projects/countreg/>.

A BibTeX entry for LaTeX users is

  @Manual{,
    title = {{countreg}: Count Data Regression},
    author = {Achim Zeileis and Christian Kleiber},
    year = {2024},
    note = {R package version 0.3-0},
    url = {https://R-Forge.R-project.org/projects/countreg/},
  }

If count data regression models zeroinfl()/hurdle() are used, please
cite:

  Zeileis A, Kleiber C, Jackman S (2008). “Regression Models for Count
  Data in R.” _Journal of Statistical Software_, *27*(8), 1-25.
  doi:10.18637/jss.v027.i08 <https://doi.org/10.18637/jss.v027.i08>.

A BibTeX entry for LaTeX users is

  @Article{,
    title = {Regression Models for Count Data in {R}},
    author = {Achim Zeileis and Christian Kleiber and Simon Jackman},
    journal = {Journal of Statistical Software},
    year = {2008},
    volume = {27},
    number = {8},
    pages = {1--25},
    doi = {10.18637/jss.v027.i08},
  }

If rootogram() is used, please cite:

  Kleiber C, Zeileis A (2016). “Visualizing Count Data Regressions
  Using Rootograms.” _The American Statistician_, *70*(3), 296-303.
  doi:10.1080/00031305.2016.1173590
  <https://doi.org/10.1080/00031305.2016.1173590>.

A BibTeX entry for LaTeX users is

  @Article{,
    title = {Visualizing Count Data Regressions Using Rootograms},
    author = {Christian Kleiber and Achim Zeileis},
    journal = {The American Statistician},
    year = {2016},
    volume = {70},
    number = {3},
    pages = {296--303},
    doi = {10.1080/00031305.2016.1173590},
  }