Bibliografia

· J. M. Howie, "Automata and Languages", Clarendon Press, Oxford (1991). · J. M. Howie, "Fundamentals of Semigroup Theory", Oxford University Press (1996). · M. V. Lawson, "Finite Automata", Chapman&Hall/CRC (2004). · J.-E. Pin, "Varieties of Formal Languages", North Oxford, London, and Plenum, New York (1986).:

· J. E. Hopcroft, R. Motwani e J. D. Ullman, "Introduction to Automata Theory, Languages, and Computation", 3ª edição, Prentice Hall (2006). · S. Eilenberg, "Automata, Languages and Machines", vol. B, Academic Press, New York (1976). . J. Almeida, "Finite Semigroups and Universal Algebra", World Scientific, Singapore (1994). · W. Wechler, "Universal Algebra for Computer Scientists", Springer-Verlag, Berlin (1992).: