To cite package 'difNLR' in publications use:

Drabinova A., Martinkova P., & Zvara K. (2018). difNLR: DIF and DDF detection by non-linear regression models. R package version 1.2.2.

Drabinova A., & Martinkova P. (2017). Detection of Differential Item Functioning with Nonlinear Regression: A Non-IRT Approach Accounting for Guessing. Journal of Educational Measurement, 54(4), 498-517.

Corresponding BibTeX entries:

  @Manual{,
    title = {{difNLR}: {DIF} and {DDF} Detection by Non-Linear
      Regression Models.},
    author = {Adela Drabinova and Patricia Martinkova and Karel Zvara},
    year = {2018},
    note = {R package version 1.2.2},
    url = {https://CRAN.R-project.org/package=difNLR},
  }

  @Article{,
    title = {{D}etection of Differential Item Functioning with
      Nonlinear Regression: {A} Non-{IRT} Approach Accounting for
      Guessing},
    author = {Adela Drabinova and Patricia Martinkova},
    year = {2017},
    journal = {Journal of Educational Measurement},
    volume = {54},
    number = {4},
    pages = {498-517},
    publisher = {Wiley Online Library},
  }