K. Zhao, and J. Wang. Genetic Programming 1998: Proceedings of the Third
Annual Conference, page 439--447. University of Wisconsin, Madison, Wisconsin, USA, Morgan Kaufmann, (22-25 July 1998)
K. Zhao, and J. Wang. Genetic Programming 1997: Proceedings of the Second
Annual Conference, page 343. Stanford University, CA, USA, Morgan Kaufmann, (13-16 July 1997)
J. Zhao, G. Kearney, and A. Soper. Late Breaking Papers at the Genetic Programming 1996
Conference Stanford University July 28-31, 1996, page 197--202. Stanford University, CA, USA, Stanford Bookstore, (28--31 July 1996)
Z. Zhang, W. Luo, and X. Wang. 2007 IEEE Congress on Evolutionary Computation, page 3751--3758. Singapore, IEEE Computational Intelligence Society, IEEE Press, (25-28 September 2007)