APA (7th ed.) Citation

Stone, D., Patton, B., & Heen, S. (2001). Difficult conversations: How to discuss what matters most. Penguin.

Chicago Style (17th ed.) Citation

Stone, Douglas, Bruce Patton, and Sheila Heen. Difficult Conversations: How to Discuss What Matters Most. London: Penguin, 2001.

MLA (9th ed.) Citation

Stone, Douglas, et al. Difficult Conversations: How to Discuss What Matters Most. Penguin, 2001.