To cite ItemResponseTrees in publications use:

Plieninger H (2020). ItemResponseTrees: IR-Tree Modeling in mirt, Mplus, or TAM. R package, https://github.com/hplieninger/ItemResponseTrees/.

Corresponding BibTeX entry:

  @Manual{,
    title = {{ItemResponseTrees}: {IR}-Tree Modeling in mirt, {Mplus},
      or {TAM}},
    author = {Hansj\"{o}rg Plieninger},
    year = {2020},
    url = {https://github.com/hplieninger/ItemResponseTrees/},
    version = {0.2.5},
    note = {R package},
  }