In addition to DM/IM books, make sure you expand your business knowledge. Knowing how customers tick and how SWOT works rarely goes out of style.
My suggestions:
- Primal Branding
 - Influence (Cialdini)
 - The Lean Startup
 - Lean In (Sandberg)
 - Think & Grow Rich
 - Selling the Invisible (Beckwith)
 - The Slight Edge
 - Excel for SEOs
 - Blue Ocean Strategy (Gladwell)
 - Crossing the Chasm
 - Decoded (Barden)
 - The Innovator's Dilemma
 - Never Eat Alone
 - Psycho Cybernetics
 - Rework (Fried)
 - The Wisdom of Psychopaths