For further reading the following books in related topics are recommended:
Bel-Enguix, Gemma, Jiménez-López, Maria Dolores and Martín-Víde, Carlos (eds.): Recent Developments in Formal Languages and Applications, Springer, Berlin, 2008.
Ésik, Zoltán, Martín-Vide, Carlos and Mitrana, Victor (eds.): Recent Advances in Formal Languages and Applications, Springer 2006.
Harrison, Michael A.: Introduction to Formal Language Theory, Addison-Wesley, 1978.
Herendi, Tamás and Nagy, Benedek: Parallel Approach of Algorithms, Typotex, Budapest, 2014.
Hopcroft, John E. and Ullmann, Jeffrey D.: Introduction to Automata Theory, Languages, and Computation. Addison-Wesley, Reading, Massachusetts, Menlo Park, California, London, Amsterdam, Don Mills, Ontario, Sidney, 1979.
Linz, Peter: An introduction to formal languages and automata, Fourth edition, Jones and Bartlett Publishers 2006.
Martín-Vide, Carlos, Mitrana, Victor and Păun, Gheorghe (eds.) Formal Languages and Applications, Springer, Berlin, 2004.
Révész, György E.: Introduction to Formal Languages, McGraw-Hill, New York, St Louis, San Francisco, Auckland, Bogota, Hamburg, Johannesburg, London, Madrid, Mexico, Montreal, New Delhi, Panama, Paris, Sao Paulo, Singapore, Sydney, Tokyo, Toronto, 1983.
Rozenberg, Grzegorz and Salomaa, Arto (eds.): Handbook of Formal Languages, 3 volumes, Springer, Heidelberg, 1997.
Salomaa, Arto: Formal Languages, Academic Press, New York, London, 1973.