APA (7th ed.) Citation

Stone Douglas, Heen, S., & Patton Bruce. (1999). Difficult conversations: How to discuss what matters most. Penguin Books.

Chicago Style (17th ed.) Citation

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

MLA (9th ed.) Citation

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