They Ask You Answer - Marcus Sheridan - The only sustainable way to do real content marketing and SEO is to answer your audience questions...no brainer...but often forgotten (video).
Building a Story Brand - Donald Miller - This book forces you to nail a simple version of your Positioning and Branding. It gets you started quickly with a solid foundation for the content on your website, your email campaigns and product branding (video).
Crossing the Chasm - Geoffrey Moore - A classic that is foundational for every Technology Marketing Executive getting to Product-Market-Fit and to Scale (video)
Start with Why - Simon Sinek's high impact work on driving Strategy from the essence of your customer's values and your own (video).
Thinking, Fast and Slow - Daniel Kahneman - 528 pages of wisdom and insights from the inventors of the field of Behavioral Science. All books that came after, around the way people make decisions, price psychology, consumer behavior, and preferences, are grounded in this masterpiece (video).
The long tail - Chris Andersen - Access to information and the ability to reach individuals with unprecedented precision has changed marketing forever.