There is no book or feed that is going to be able to teach you how to punch like a boxer. It might be able to give you an idea but you will never become effective with it. Over the last 25 years we have had about 20 to 25 MMA, kick boxers, shot fighters, ex. Come into are gym to learn how to punch like a boxer.
Every one of them left with a better knowledge of punching, but the one thing they didn't like about the way a boxer punches is that it commits your feet to the ground to produce power through the punch. My best advice to you is find a local boxing gym spend sometime with the coaches get in the ring and just box maybe even have a couple of fights once you think you have the jest of it then you can find a way to fit it into your MMA fighting style.