APA (7th ed.) Citation

Stone, D., Heen, S., & Patton, B. (1999). Difficult conversations: How to discuss what matters most. Penguin Group.

Chicago Style (17th ed.) Citation

Stone, Douglas, Sheila Heen, and Bruce Patton. Difficult Conversations: How to Discuss What Matters Most. New York: Penguin Group, 1999.

MLA (9th ed.) Citation

Stone, Douglas, et al. Difficult Conversations: How to Discuss What Matters Most. Penguin Group, 1999.