APA (7th ed.) Citation

Thorpy, M. J., & Yager, J. (1991). The encyclopedia of sleep and sleep disorders. Facts on File.

Chicago Style (17th ed.) Citation

Thorpy, Michael J., and Jan Yager. The Encyclopedia of Sleep and Sleep Disorders. New York, NY [u.a.]: Facts on File, 1991.

MLA (9th ed.) Citation

Thorpy, Michael J., and Jan Yager. The Encyclopedia of Sleep and Sleep Disorders. Facts on File, 1991.