To cite mixtools in publications use:

Tatiana Benaglia, Didier Chauveau, David R. Hunter, Derek Young (2009). mixtools: An R Package for Analyzing Finite Mixture Models. Journal of Statistical Software, 32(6), 1-29. URL http://www.jstatsoft.org/v32/i06/.

Corresponding BibTeX entry:

  @Article{,
    title = {{mixtools}: An {R} Package for Analyzing Finite Mixture
      Models},
    author = {Tatiana Benaglia and Didier Chauveau and David R. Hunter
      and Derek Young},
    journal = {Journal of Statistical Software},
    year = {2009},
    volume = {32},
    number = {6},
    pages = {1--29},
    url = {http://www.jstatsoft.org/v32/i06/},
  }