1. V. Antimirov, Partial derivatives of regular expressions and finite automaton constructions, Theoretical Computer Science, 155, 291–319 (1996).
2. J. Berstel and D. Perrin Theory of codes, Academic Press (1985).
3. J. Berstel and C. Reutenauer, Rational Series and Their Languages (EATCS Monographs on Theoretical Computer Science, Springer-Verlag, Berlin, 1988).
4. J.A. Brzozowski. Derivatives of regular expressions. J. Assoc. Comput. Mach., 11(4):481–494, 1964.
5. J. H. Conway, Regular Algebras and Finite Machines, Chapman and Hall, London 1974.