The Theory of Computation or Automata Theory is the most difficult subject of computer science & engineering.
So, firstly you will have to read theory and then you can move to practical.Â
My Guru (Who is a Professor in USICT, GGSIPU) told me to go for Peter Linz if you will enter in the world of theory of computation.Â
In Peter Linz, english is very simple but automata theory terms are complex.
Second book is Theory of Computer Science: Automata, Languages and Computation by K.L.P. Mishra & N. Chandrasekaran published by PHI publications.
This book is sufficient for GATE and NET.
Third book is Automata Theory Language & Computation by Hopcroft Published by Pearson.
