WorkLife with Adam Grant. Organisational Psychologist
Brené Brown - The Power of Vulnerability
Liz Wiseman, Multipliers: How the Best Leaders Make Everyone Smarter
Julie Zhuo, The Making of a Manager: What to Do When Everyone Looks to You
Simon Sinek, Leaders Eat Last: Why Some Teams Pull Together and Others Don't
Patrick Lencioni, The Five Dysfunctions of a Team: A Leadership Fable
Brené Brown, Dare to Lead: Brave Work. Tough Conversations. Whole Hearts.
Paul Sloane, The Leader’s Guide to Lateral Thinking Skills
Edward de Bono, Six Thinking Hats
Better Managers = Better Business, by Pete Fullard
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
Penny Mallory: Develop Mental Toughness
Nick Howell: Great Coaching Questions