To cite package depmix in publications, use the following:

Ingmar Visser (2007). Depmix: An R-package for fitting mixture models on mixed multivariate data with Markov dependencies. R-package manual and introduction into Dependent Mixture models

Corresponding BibTeX entry:

  @Article{,
    title = {{depmix}: An R-package for fitting mixture models on mixed
      multivariate data with Markov dependencies},
    author = {Ingmar Visser},
    journal = {R-package manual},
    year = {2007},
    url = {http://cran.r-project.org},
  }