The most influential book on this professional marketer is…

The book 'Influence' by Robert Cialdini has had the biggest impact on the professional marketer. It made them realize that there are real commercial applications for the principles of persuasion mentioned in the book. The six key principles of persuasion identified in the book are consistency, commitment, authority, likability, reciprocity, and social proof. This book got the marketer hooked on the subject and has been very influential in their career.