If you use exams()/exams2pdf() please cite:

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/.

If you use exams2html()/exams2moodle()/exams2qti12(), please cite:

Achim Zeileis, Nikolaus Umlauf, Friedrich Leisch (2012). Flexible Generation of E-Learning Exams in R: Moodle Quizzes, OLAT Assessments, and Beyond. Working Paper 2012-27. Working Papers in Economics and Statistics, Research Platform Empirical and Experimental Economics, Universitaet Innsbruck. URL http://EconPapers.RePEc.org/RePEc:inn:wpaper:2012-27

Corresponding BibTeX entries:

  @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/},
  }
  @TechReport{,
    title = {Flexible Generation of E-Learning Exams in {R}: {Moodle}
      Quizzes, {OLAT} Assessments, and Beyond},
    author = {Achim Zeileis and Nikolaus Umlauf and Friedrich Leisch},
    institution = {Working Papers in Economics and Statistics, Research
      Platform Empirical and Experimental Economics, Universit\"at
      Innsbruck},
    year = {2012},
    type = {Working Paper},
    number = {2012-27},
    month = {December},
    url = {http://EconPapers.RePEc.org/RePEc:inn:wpaper:2012-27},
  }