To cite deltaPlotR in publications use:

David Magis, Bruno Facon (2014). deltaPlotR: An R Package for Differential Item Functioning Analysis with Angoff's Delta Plot. Journal of Statistical Software, Code Snippets, 59(1), 1-19. URL http://www.jstatsoft.org/v59/c01/.

Corresponding BibTeX entry:

  @Article{,
    title = {{deltaPlotR}: An {R} Package for Differential Item
      Functioning Analysis with Angoff's Delta Plot},
    author = {David Magis and Bruno Facon},
    journal = {Journal of Statistical Software, Code Snippets},
    year = {2014},
    volume = {59},
    number = {1},
    pages = {1--19},
    url = {http://www.jstatsoft.org/v59/c01/},
  }