To cite EMMIXuskew in publications use:

Sharon X. Lee, Geoffrey J. McLachlan (2013). EMMIXuskew: An R Package for Fitting Mixtures of Multivariate Skew $t$ Distributions via the EM Algorithm. Journal of Statistical Software, 55(12), 1-22. URL http://www.jstatsoft.org/v55/i12/.

Corresponding BibTeX entry:

  @Article{,
    title = {{EMMIXuskew}: An {R} Package for Fitting Mixtures of
      Multivariate Skew $t$ Distributions via the {EM} Algorithm},
    author = {Sharon X. Lee and Geoffrey J. McLachlan},
    journal = {Journal of Statistical Software},
    year = {2013},
    volume = {55},
    number = {12},
    pages = {1--22},
    url = {http://www.jstatsoft.org/v55/i12/},
  }