AAAI Press, The MIT Press, 1995. 316 pages.
Palgrave MacMillan, NY, 2008, ISBN ? 13 : 978 0 230 51548 2, 365 pages.
Volume V of the Santa Fé Institute Studies in the Sciences of Complexity, AddisonWesley Pub. Cy. N.Y. 1988. 317 p.