1.
Garey MR, Johnson DS. Computers and Intractability: A Guide to the Theory of NP-Completeness. Vol A series of books in the mathematical sciences. W. H. Freeman; 1979.
2.
Rayward-Smith VJ. A First Course in Computability. Vol Computer science texts. Blackwell Scientific; 1986.
3.
Harry R. Lewis. Elements of the Theory of Computation. Prentice-Hall; 1998.
4.
Sipser M. Introduction to the Theory of Computation. 3rd ed., International ed. Cengage Learning; 2013.
5.
Hopcroft JohnE, Motwani R, Ullman JD. Introduction to Automata Theory, Languages, and Computation. Pearson Education; 2003.