Cita APA (7a ed.)

American Psychological Association, Pressman, M. R., & Orr, W. C. (1997). Understanding sleep: The evaluation and treatment of sleep disorders. American Psychological Association.

Cita Chicago Style (17a ed.)

American Psychological Association, Mark R. Pressman, y William C. Orr. Understanding Sleep: The Evaluation and Treatment of Sleep Disorders. Washington: American Psychological Association, 1997.

Cita MLA (9a ed.)

American Psychological Association, et al. Understanding Sleep: The Evaluation and Treatment of Sleep Disorders. American Psychological Association, 1997.