How to Win Friends and Influence People by Dale Carnegie

The Psychology of Selling by Brian Tracy

Permission Marketing: Turning Strangers into Friends and Friends into Customers by Seth Godin

Crossing The Chasm: Marketing and Selling Disruptive Products To Mainstream Customers by Geoffrey A. Moore

Hyper Sales Growth: Street-Proven Systems & Processes. How to Grow Quickly & Profitably by Jack Daly