@Article{EspondaEtal05b,
  author =	 "F. Esponda and E. S. Ackley and S. Forrest and
                  P. Helman",
  title =	 "On-line Negative Databases (with experimental
                  results)",
  journal =	 {International Journal of Unconventional Computing},
  Volume =	 {1},
  pages =	 {201--220},
  Number =	 {3},
  year =	 {2005}
}