To cite tolerance in publications use:

Derek S. Young (2010). tolerance: An R Package for Estimating Tolerance Intervals. Journal of Statistical Software, 36(5), 1-39. URL http://www.jstatsoft.org/v36/i05/.

Corresponding BibTeX entry:

  @Article{,
    title = {{tolerance}: An {R} Package for Estimating Tolerance
      Intervals},
    author = {Derek S. Young},
    journal = {Journal of Statistical Software},
    year = {2010},
    volume = {36},
    number = {5},
    pages = {1--39},
    url = {http://www.jstatsoft.org/v36/i05/},
  }