Open the PDF. Read just the part that answers your question. Then close the PDF.
However, anyone who has worked through this book knows the challenge. The end-of-chapter problems are designed not just to test recall, but to push your understanding of convolution, Z-transforms, filter design, and FFT algorithms. This leads thousands of learners to search for the same phrase every semester:
Is it the convolution limits? The Z-transform partial fraction expansion? The passband ripple specification? Write down a specific question.
When you type this keyword into a search engine, you are likely to encounter a mix of resources. It is rarely a simple "click and download" process. Here is what you will typically find: