To cite package mlbench in publications use:

Friedrich Leisch & Evgenia Dimitriadou (2010). mlbench: Machine Learning Benchmark Problems. R package version 2.1-1.

To cite data sets from the UCI repository (as indicated in the help pages) use:

Newman, D.J. & Hettich, S. & Blake, C.L. & Merz, C.J. (1998). UCI Repository of machine learning databases [http://www.ics.uci.edu/~mlearn/MLRepository.html]. Irvine, CA: University of California, Department of Information and Computer Science.

Corresponding BibTeX entries:

  @Manual{,
    title = {mlbench: Machine Learning Benchmark Problems},
    author = {Friedrich Leisch and Evgenia Dimitriadou},
    year = {2010},
    note = {R package version 2.1-1},
  }

  @Misc{,
    author = {D.J. Newman and S. Hettich and C.L. Blake and C.J. Merz},
    year = {1998},
    title = {UCI Repository of machine learning databases},
    url = {http://www.ics.uci.edu/~mlearn/MLRepository.html},
    institution = {University of California, Irvine, Dept. of
      Information and Computer Sciences},
  }