If you are preparing for that follow a classical control syllabus with many numerical problems, the Bakshi & Bakshi book is a solid choice. For a stronger conceptual foundation or research‑oriented learning, prefer Ogata or Nagrath & Gopal.
To help you decide if this is the right resource, (e.g., Root Locus, PID controllers, or Frequency Response)?
of the 2020 edition, useful for checking specific chapters or diagrams. Google Books Alternative Resources
: Definitions, open-loop vs. closed-loop systems, and feedback characteristics.
If you manage to get the PDF, use it as a companion, not a crutch. Draw the block diagrams by hand. Solve the numericals without looking at the answers. Only then will you truly master Control System Engineering.