To cite DFIT in publications use:

Victor H. Cervantes (2014). DFIT: An R package for the Differential Functioning of Items and Tests framework. Instituto Colombiano para la Evaluacion de la Educacion [ICFES], Bogota, Colombia.

Corresponding BibTeX entry:

  @Manual{,
    title = {DFIT: An R package for the Differential Functioning of
      Items and Tests framework},
    author = {{Victor H. Cervantes}},
    organization = {Instituto Colombiano para la Evaluacion de la
      Educacion [ICFES]},
    address = {Bogota, Colombia},
    year = {2014},
  }