To cite GPArotateDF in publications use:

I.Jennrich R (2004). “Derivative free gradient projection algorithms for rotation.” Psychometrika, 69, 475–480.

Bernaards CA, I.Jennrich R (2005). “Gradient Projection Algorithms and Software for Arbitrary Rotation Criteria in Factor Analysis.” Educational and Psychological Measurement, 65, 676–696.

Corresponding BibTeX entries:

  @Article{,
    author = {Robert I.Jennrich},
    year = {2004},
    title = {Derivative free gradient projection algorithms for
      rotation},
    journal = {Psychometrika},
    volume = {69},
    issue = {3},
    pages = {475--480},
  }

  @Article{,
    author = {Coen A. Bernaards and Robert I.Jennrich},
    year = {2005},
    title = {Gradient Projection Algorithms and Software for Arbitrary
      Rotation Criteria in Factor Analysis},
    journal = {Educational and Psychological Measurement},
    volume = {65},
    issue = {5},
    pages = {676--696},
  }