I have many but here are two that I have read recently and found valuable:

- The Essential Marcus Aurelius (https://www.amazon.com/Essential-Aurelius-Tarcher-Cornerston...)

- Leading by Alex Ferguson (https://www.amazon.ca/Leading-Alex-Ferguson/dp/1473621178)

I admire the fact that this man has been able to recreate success with different teams and all kinds of personalities for close to 3 decades.