1. Theory of Self-Reproducing Automata;von Neumann,1966
2. Universality and complexity in cellular automata;Wolfram;Physica D,1984
3. Undecidability of CA classification schemes;Culik;Complex Systems,1988
4. Formal language characterizations of cellular automaton limit sets;Hurd;Complex Systems,1987
5. Algebraic and Automata-Theoretic Properties of Formal Languages;Ginsburg,1975