To cite TestDesign in publications, use:

Choi S, Lim S (2020). TestDesign: Optimal Test Design Approach to Fixed and Adaptive Test Construction. R package version 1.1.3, https://CRAN.R-project.org/package=TestDesign.

Corresponding BibTeX entry:

  @Manual{,
    title = {{TestDesign}: Optimal Test Design Approach to Fixed and
      Adaptive Test Construction},
    author = {Seung W. Choi and Sangdon Lim},
    year = {2020},
    note = {R package version 1.1.3},
    url = {https://CRAN.R-project.org/package=TestDesign},
  }