To cite the 'tmt' package in publications use:

Steinfeld, J. and Robitzsch, A. (2019). tmt: Estimation of the Rasch Model for Multistage Tests. R package version 0.2.1-0. https://CRAN.R-project.org/package=tmt

Corresponding BibTeX entry:

  @Manual{,
    title = {tmt: Estimation of the Rasch Model for Multistage Tests},
    author = {Jan Steinfeld and Alexander Robitzsch},
    year = {2019},
    note = {R package version 0.2.1-0},
    url = {https://CRAN.R-project.org/package=tmt},
  }