H. Spada, A. Meier, N. Rummel, and S. Hauser. Proceedings of th 2005 conference on Computer support for collaborative learning: learning 2005: the next 10 years!, page 622–631. International Society of the Learning Sciences, (2005)
L. Jones, S. Al-Sakran, und J. Koza. Genetic Programming Theory and Practice III, Volume 9 von Genetic Programming, Kapitel 3, Springer, Ann Arbor, (12-14 May 2005)