K. Sastry, D. Johnson, D. Goldberg, and P. Bellon. IlliGAL Report, 2003014. Department of General Engineering University of
Illinois at Urbana-Champaign, 117 Transportation Building, 104 S. Mathews Avenue,
Urbana, IL 61801, USA, (April 2003)
U. O'Reilly, and D. Goldberg. Genetic Programming 1998: Proceedings of the Third
Annual Conference, page 269--277. University of Wisconsin, Madison, Wisconsin, USA, Morgan Kaufmann, (22-25 July 1998)