Automata Theory, Languages, and Computation , Addison-Wesley Publishing, Reading Massachusetts, 1979. ISBN 81-7808-347-7 . Rautenberg, Wolfgang (2010), A Concise Introduction to Mathematical Logic (3rd ed.), New York : Springer Science+Business Media , doi : 10.1007/978-1-4419-1221-3 , ISBN   978-1-4419-1220-6 , http://www.springerlink.com/content/978-1-4419-1220-6/   . Grzegorz Rozenberg , Arto Salomaa , Handbook of Formal