Control systems are often drawn as interconnected blocks. Poley provides a cheat sheet of reduction rules: series, parallel, and feedback (G/(1+GH)). The PDF includes dozens of worked examples where a messy diagram is simplified into a single transfer function—a critical skill for any control engineer.
Covers modeling and design for more complex systems, supplemented in later editions with expanded chapters on state-space methods Discrete and Digital Control: Control Theory Fundamentals Richard Poley Pdf
If you have the PDF, keep it on your desktop as a quick refresher. It’s essentially a 100-page cheat sheet for the heavy-hitting textbooks. Control systems are often drawn as interconnected blocks