D. Wood. Genetic Programming 1998: Proceedings of the Third
Annual Conference, page 731--734. University of Wisconsin, Madison, Wisconsin, USA, Morgan Kaufmann, (22-25 July 1998)
D. Wood, J. Chen, E. Lemieux, and W. Cedeno. Proceedings of the Genetic and Evolutionary
Computation Conference, 2, page 1835--1842. Orlando, Florida, USA, Morgan Kaufmann, (13-17 July 1999)