If I ever met Donald H. Perkins, I would go to his home and delete his word processor. This man should never write, much less write a physics textbook. I had the misfortune of having to use this textbook for my undergraduate particle physics courses. He pulled equations out of a vacuum with no mathematical justifications whatsoever. Worse yet, these equations would change based on various scenarios and conditions that he never outlined. The problems at the end of the chapter were poorly written; and there is a special place in hell for people who use v and nu in the same equation. His attempts at the electroweak chapters were beyond horrid. Stay away from this textbook. If your professor assigns it, don't sign up for the class.