Assuming you have secured a legal PDF (e.g., through your university library), here is a study strategy to maximize its value.
If you manage to locate a legitimate copy (or purchase the physical book), here is the critical knowledge architecture you will encounter. nonlinear control khalil pdf
The PDF is worth its weight in gold for Chapter 4, where Khalil explains the Jacobian linearization (indirect method) versus constructing a Lyapunov function (direct method). For a nonlinear engineer, knowing when to use which method is the core skill, and Khalil provides the flowcharts and theorems to decide. Report: Review of "Nonlinear Systems" by Hassan K