The Theory of Computation is a branch of computer science that deals with the study of algorithms, automata, and formal languages. The book by AA Puntambekar is a popular textbook on this subject, widely used in universities and colleges.
If you're looking for a downloadable PDF of the book, you can try searching online repositories or websites that host free e-books. However, I must remind you that downloading copyrighted materials without permission is against the law.