To cite Countr in publications use:

Kharrat T, Boshnakov GN, McHale I, Baker R (2019). “Flexible Regression Models for Count Data Based on Renewal Processes: The Countr Package.” Journal of Statistical Software, 90(13), 1–35. doi:10.18637/jss.v090.i13.

Corresponding BibTeX entry:

  @Article{,
    title = {Flexible Regression Models for Count Data Based on Renewal
      Processes: The {Countr} Package},
    author = {Tarak Kharrat and Georgi N. Boshnakov and Ian McHale and
      Rose Baker},
    journal = {Journal of Statistical Software},
    year = {2019},
    volume = {90},
    number = {13},
    pages = {1--35},
    doi = {10.18637/jss.v090.i13},
  }