Bibliografia

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

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)) Introduction to Automata Theory, Languages and Computation
J. Almeida (World Scientific, Singapore (1994)) Finite Semigroups and Universal Algebra
G. Rozenbeg e A. Salomaa (Eds.) (Springer-Verlag, Berlin (1997)) Handbook of Formal Languages, Vol. 1