Converting Regular Expression to NFA
References
Hopcroft, J. E., Motwani, R., & Ullman, J. D. (2006). Introduction to Automata Theory, Languages, and Computation (3rd ed.). Pearson Education.
Thompson, K. (1968). Programming Techniques: Regular expression search algorithm. Communications of the ACM, 11(6), 419-422.
Sipser, M. (2012). Introduction to the Theory of Computation (3rd ed.). Cengage Learning.
Aho, A. V., Lam, M. S., Sethi, R., & Ullman, J. D. (2006). Compilers: Principles, Techniques, and Tools (2nd ed.). Pearson Education.
Kozen, D. C. (1997). Automata and Computability. Springer.