K. Wolff, and P. Nordin. Proceedings of the 2nd IEEE-RAS International
Conference on Humanoid Robots, page 99--106. Institute of Electrical and Electronics Engineers,
Inc., (2001)
T. Paul, and H. Iba. Genetic Programming Theory and Practice IV, volume 5 of Genetic and Evolutionary Computation, chapter 10, Springer, Ann Arbor, (11-13 May 2006)
W. Langdon, and P. Nordin. Genetic Programming, Proceedings of EuroGP'2001, volume 2038 of LNCS, page 313--324. Lake Como, Italy, Springer-Verlag, (18-20 April 2001)