Varela, Francisco J.; Maturana, Humberto R.; & Uribe, R. (1974). “Autopoiesis: the organization of living systems, its characterization and a model”

Good historical paper. This shows an early CA/ABM type model where they demonstrate the spontaneous formation of autopoietic entities, given their assumptions. In this case it means a simulated border forms around a simulated enzyme on a 2-D lattice. It is a nice demonstration of what they mean when they talk about continuously self-producing entities, and focus on the self-maintenance instead of the reproduction as essential to life.