APA (7th ed.) Citation

Sinek, S. (2011). Start with why: How great leaders inspire everyone to take action (1st published.). Portfolio Penguin.

Chicago Style (17th ed.) Citation

Sinek, Simon. Start with Why: How Great Leaders Inspire Everyone to Take Action. 1st published. London[etc.]: Portfolio Penguin, 2011.

MLA (9th ed.) Citation

Sinek, Simon. Start with Why: How Great Leaders Inspire Everyone to Take Action. 1st published. Portfolio Penguin, 2011.