To cite the sft package in publications use:

Houpt, J.W., Blaha, L.M., McIntire, J.P., Havig, P.R. and Townsend, J.T. (2014) Systems Factorial Technology with R. Behavior Research Methods, 46, 307-330.

Corresponding BibTeX entry:

    title = {Systems Factorial Technology with R},
    author = {Joseph Houpt and Leslie Blaha and John McIntire and Paul
      Havig and James Townsend},
    journal = {Behavior Research Methods},
    pages = {307-330},
    volume = {46},
    year = {2014},