To cite exams in publications use:

Bettina Gruen, Achim Zeileis (2009). Automatic Generation of Exams in R. Journal of Statistical Software 29(10), 1-14. URL http://www.jstatsoft.org/v29/i10/.

Corresponding BibTeX entry:

  @Article{,
    title = {Automatic Generation of Exams in {R}},
    author = {Bettina Gr\"un and Achim Zeileis},
    journal = {Journal of Statistical Software},
    year = {2009},
    volume = {29},
    number = {10},
    pages = {1--14},
    url = {http://www.jstatsoft.org/v29/i10/},
  }