5 booksFormal Languages & Automata Title Author Difficulty Priority An Introduction to Formal Languages and Automata Peter Linz Intermediate high Automata and Computability Dexter Kozen Advanced medium Automata Computability and Complexity Elaine Rich Advanced medium Introduction to Automata Theory Languages and Computations Hopcroft, Motwani & Ullman Advanced high Programming Languages: Application and Interpretation Shriram Krishnamurthi Advanced medium