To cite sms in publications use:

Kavroudakis D (2015). “sms: An R Package for the Construction of Microdata for Geographical Analysis.” Journal of Statistical Software, 68(2), 1–23. doi:10.18637/jss.v068.i02.

Corresponding BibTeX entry:

  @Article{,
    title = {{sms}: An {R} Package for the Construction of Microdata
      for Geographical Analysis},
    author = {Dimitris Kavroudakis},
    journal = {Journal of Statistical Software},
    year = {2015},
    volume = {68},
    number = {2},
    pages = {1--23},
    doi = {10.18637/jss.v068.i02},
  }