To cite irtplay in publications use:

Lim H, Wells CS (2022). “irtplay: An R Package for Unidimensional Item Response Theory Modeling.” Journal of Statistical Software, 103(12), 1–42. doi:10.18637/jss.v103.i12.

Corresponding BibTeX entry:

  @Article{,
    title = {{irtplay}: An {R} Package for Unidimensional Item Response
      Theory Modeling},
    author = {Hwanggyu Lim and Craig S. Wells},
    journal = {Journal of Statistical Software},
    year = {2022},
    volume = {103},
    number = {12},
    pages = {1--42},
    doi = {10.18637/jss.v103.i12},
  }