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)
Stephen Covey: The 7 Habits of Highly Effective People
R. Michael Anderson: Leadership Mindset 2.0
Nick Howell: Great Coaching Questions
Julie Starr: The Coaching Manual
John Kotter: Leading Change
Daniel Kahneman: Thinking, Fast and Slow
Caspar Craven: Be More Human
Forgiveness by Iyanla Vanzant
The Five Dysfunctions of a Team: A Leadership Fable by Patrick M. Lencioni
Energy Leadership: The 7 Level Framework for Mastery in Life and Business by Bruce D Schneider
The Fear-Fighter Manual: Lessons from a Professional Troublemaker by Luvvie Ajayi Jones