To cite PST in publications use:

Alexis Gabadinho, Gilbert Ritschard (2016). Analyzing State Sequences with Probabilistic Suffix Trees: The PST R Package. Journal of Statistical Software, 72(3), 1-39.<doi:10.18637/jss.v072.i03>

Corresponding BibTeX entry:

  @Article{,
    title = {Analyzing State Sequences with Probabilistic Suffix Trees:
      The {PST} {R} Package},
    author = {Alexis Gabadinho and Gilbert Ritschard},
    journal = {Journal of Statistical Software},
    year = {2016},
    volume = {72},
    number = {3},
    pages = {1--39},
    doi = {10.18637/jss.v072.i03},
  }