I notice you're asking for an article about "Digital Signal Processing" by Proakis, specifically the and mentioning a pdfrar file.
The 5th edition (2013) exists, but many professors prefer the 4th. Reasons include: digital signal processing proakis 4th edition pdfrar
Almost every engineering library has Proakis 4th. Many universities offer free scanner use—you can legally scan chapters for personal study (fair use). I notice you're asking for an article about
Digital Signal Processing: Principles, Algorithms, and Applications (4th Edition) and Applications (4th Edition)