To cite kernlab in publications use:

Karatzoglou A, Smola A, Hornik K, Zeileis A (2004). “kernlab – An S4 Package for Kernel Methods in R.” Journal of Statistical Software, 11(9), 1–20. http://www.jstatsoft.org/v11/i09/.

Corresponding BibTeX entry:

  @Article{,
    title = {kernlab -- An {S4} Package for Kernel Methods in {R}},
    author = {Alexandros Karatzoglou and Alex Smola and Kurt Hornik and
      Achim Zeileis},
    journal = {Journal of Statistical Software},
    year = {2004},
    volume = {11},
    number = {9},
    pages = {1--20},
    url = {http://www.jstatsoft.org/v11/i09/},
  }