A. Torralba, K. Murphy, W. Freeman, and M. Rubin. Computer Vision, 2003. Proceedings. Ninth IEEE International Conference
on, page 273--280 vol.1. (2003)
J. Koza, S. Al-Sakran, and L. Jones. Genetic Programming Theory and Practice IV, volume 5 of Genetic and Evolutionary Computation, chapter 4, Springer, Ann Arbor, (11-13 May 2006)