To cite isotone in publications use:

de Leeuw J, Hornik K, Mair P (2009). “Isotone Optimization in R: Pool-Adjacent-Violators Algorithm (PAVA) and Active Set Methods.” Journal of Statistical Software, 32(5), 1–24. http://www.jstatsoft.org/v32/i05/.

Corresponding BibTeX entry:

  @Article{,
    title = {Isotone Optimization in {R}: Pool-Adjacent-Violators
      Algorithm (PAVA) and Active Set Methods},
    author = {Jan {de Leeuw} and Kurt Hornik and Patrick Mair},
    journal = {Journal of Statistical Software},
    year = {2009},
    volume = {32},
    number = {5},
    pages = {1--24},
    url = {http://www.jstatsoft.org/v32/i05/},
  }