Pietro Speroni di Fenizio: "Artificial Chemistries (an introduction) " Bulletin of the European Association for Theoretical Computer Science 76(2002),128-141.
A. Lindgren, and K. Eriksson. Proceedings of the Ninth International Conference on the Simulation and Synthesis of Living Systems, ALIFE'9, page 456. Boston, (12-15 September 2004)
J. Busch, and W. Banzhaf. Proceedings, Fourth International Conference on MultiAgent Systems, page 371--372. Boston, MA, USA, IEEE Computer Society, (July 2000)