Here's a short list of influential texts, many of which I've bought multiple times because they're so good, I have to share them:

How to Win Friends and Influence People
by Dale Carnegie

The Rise of the Creative Class
by Richard Florida

Positioning
by Al Ries and Jack Trout

Brand Warfare
by David F. D'Allesandro

The Brand Gap
by Marty Neumeier

Designing Brand Identity
by Alina Wheeler

Universal Principles of Design
by William Lidwell, Kritina Holden and Jill Butler