Please cite the mpt package by the following reference:

Wickelmaier F, Zeileis A (2011). “Multinomial processing tree models in R.” Presented at the R User Conference 2011, August 16-18, Coventry, UK, https://www.R-project.org/conferences/useR-2011/TalkSlides/Contributed/17Aug_1705_FocusV_3-Psychometrics_1-Wickelmaier.pdf.

Corresponding BibTeX entry:

  @Misc{,
    title = {Multinomial processing tree models in {R}},
    author = {Florian Wickelmaier and Achim Zeileis},
    year = {2011},
    note = {Presented at the R User Conference 2011, August 16-18,
      Coventry, UK},
    url =
      {https://www.R-project.org/conferences/useR-2011/TalkSlides/Contributed/17Aug_1705_FocusV_3-Psychometrics_1-Wickelmaier.pdf},
  }