To cite package ‘SNSequate’ in publications use:

  Gonz'alez, J., (2014). SNSequate: Standard and Nonstandard
  Statistical Models and Methods for Test Equating. *Journal of
  Statistical Software*, *59*(7), 1-30.

A BibTeX entry for LaTeX users is

  @Article{,
    doi = {10.18637/jss.v059.i07},
    url = {https://www.jstatsoft.org/v59/i07/},
    year = {2014},
    journal = {Journal of Statistical Software},
    volume = {59},
    number = {7},
    pages = {1--30},
    author = {Jorge Gonz'alez},
    title = {{SNSequate}: Standard and Nonstandard Statistical Models and 
  Methods for Test Equating},
  }