Paul Sloane, The Leader’s Guide to Lateral Thinking Skills
Paul Sloane, How to be a Brilliant Thinker
Paul Sloane, Lateral Thinking for Every Day
Fermat’s Last Theorem, Simon Singh
Edward de Bono, Six Thinking Hats
How to Win Friends and Influence People, Dale Carnegie
Atomic Habits, James Clear
The Innovators Dilemma by Clayton M Christensen
Freakonomics - Steve Dubner
Better Managers = Better Business, by Pete Fullard
McKinsey Quarterly (a wide range of leadership, management and strategic thinking)
Harvard Business Review (a wide range of leadership thinking)
David Clutterbuck (a good resource for coaching and mentoring thinking)
William Buist: Intentional Mastery
Stephen Covey: The 7 Habits of Highly Effective People