A. Hauptman, and M. Sipper. Genetic Programming, volume 3447 of Lecture Notes in Computer Science, Springer Berlin / Heidelberg, 10.1007/978-3-540-31989-4_11.(2005)
L. Yaeger. Artificial Life III, Vol. XVII of SFI Studies in the
Sciences of Complexity, Santa Fe Institute, page 263--298. Los Alamos, New Mexico, Addison-Wesley, (1993)
R. Poli, W. Langdon, and N. McPhee. Published via http://lulu.com and freely
available at
http://www.gp-field-guide.org.uk, (2008)(With contributions by J. R. Koza).