D. Howard, and S. Roberts. GECCO 2002: Proceedings of the Genetic and
Evolutionary Computation Conference, page 1097--1104. New York, Morgan Kaufmann Publishers, (9-13 July 2002)
T. Hoang, N. Hoai, R. McKay, and D. Essam. Genetic Programming Theory and Practice III, volume 9 of Genetic Programming, chapter 11, Springer, Ann Arbor, (12-14 May 2005)