D. Cho, and B. Zhang. Proceedings 4th International Symposium on Artificial
Life and Robotics, page 236--239. B-Con Plaza, Beppu, Oita, Japan, (19-22 January 1999)
K. Kim, S. Lim, and S. Cho. Intelligent Data Engineering and Automated Learning -
IDEAL 2004, 5th International Conference, Proceedings, volume 3177 of Lecture Notes in Computer Science, page 813--819. Exeter, UK, Springer, (August 2004)
B. Zhang, and D. Cho. Genetic Programming 1998: Proceedings of the Third
Annual Conference, page 431--439. University of Wisconsin, Madison, Wisconsin, USA, Morgan Kaufmann, (22-25 July 1998)