Bibliografia

Automata and Languages: J. M. Howie Clarendon Press, Oxford (1991)
An Introduction to Semigroup Theory: J. M. Howie Academic Press, London (1976)
Finite Automata: M. V. Lawson Chapman & Hall/CRC (2004)
Varieties of Formal Languages: J. E. Pin North Oxford, London, and Plenum, New York (1986)
Universal Algebra for Computer Scientists: W. Wechler Springer-Verlag, Berlin (1992)

Introduction to Automata Theory, Languages and Computation: J. E. Hopcroft, R. Motwani e J. D. Ullman Addison-Wesley Publ. Co., Massachusetts (várias edições)
Introduction to Automata Theory, Languages and Computation: J. E. Hopcroft e J. D. Ullman Addison-Wesley Publ. Co., Massachusetts (1979)
Finite Semigroups and Universal Algebra: J. Almeida World Scientific, Singapore (1994)
Handbook of Formal Languages, Vol. 1: G. Rozenbeg e A. Salomaa (Eds.) Springer-Verlag, Berlin (1997)