K. Yanai, and H. Iba. GECCO 2005: Proceedings of the 2005 conference on
Genetic and evolutionary computation, 2, page 1775--1776. Washington DC, USA, ACM Press, (25-29 June 2005)
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)