1. A note about minimal non-deterministic automata;Arnold;Bull. European Assoc. Theoret. Comput. Sci.,1992
2. Automaticity III: Polynomial automaticity, context-free languages, and fixed points of morphisms;Glaister,1995
3. Polynomial automaticity, context-free languages and fixed points of morphisms;Glaister,1996
4. Introduction to Automata Theory, Languages and Computation;Hopcroft,1979
5. The structure and complexity of minimal NFA's over a unary alphabet;Jiang;Internat. J. Found. Comput. Sci.,1991