Z. Oplatkova, and I. Zelinka. GECCO 2006: Proceedings of the 8th annual conference
on Genetic and evolutionary computation, 1, page 949--950. Seattle, Washington, USA, ACM Press, (8-12 July 2006)
W. Langdon, and R. Poli. Genetic Programming 1998: Proceedings of the Third
Annual Conference, page 193--201. University of Wisconsin, Madison, Wisconsin, USA, Morgan Kaufmann, (22-25 July 1998)