To cite lordif in publications, use:

Choi S, Gibbons L, Crane P (2011). “lordif: An R Package for Detecting Differential Item Functioning Using Iterative Hybrid Ordinal Logistic Regression/Item Response Theory and Monte Carlo Simulations.” Journal of Statistical Software. doi:10.18637/jss.v039.i08.

Corresponding BibTeX entry:

  @Article{,
    title = {{lordif}: An R Package for Detecting Differential Item
      Functioning Using Iterative Hybrid Ordinal Logistic
      Regression/Item Response Theory and Monte Carlo Simulations},
    author = {Seung W. Choi and Laura E. Gibbons and Paul K. Crane},
    year = {2011},
    doi = {10.18637/jss.v039.i08},
    journal = {Journal of Statistical Software},
  }