To cite package ‘tppcm’ in publications use:

  Tsai, J.-W. (2026). tppcm: Step discriminations for the two-parameter
  partial credit model on top of TAM. R package version 0.1.0.

A BibTeX entry for LaTeX users is

  @Manual{,
    title = {{tppcm}: Step Discriminations for the Two-Parameter Partial Credit Model on Top of {TAM}},
    author = {Jie-Wen Tsai},
    year = {2026},
    note = {R package version 0.1.0},
  }

  Yu, M.-N. (1991). A two-parameter partial credit model (Doctoral
  dissertation). University of Illinois at Urbana-Champaign.

A BibTeX entry for LaTeX users is

  @PhdThesis{,
    title = {A Two-Parameter Partial Credit Model},
    author = {Min-Ning Yu},
    school = {University of Illinois at Urbana-Champaign},
    year = {1991},
  }