Cita APA (7th ed.)

ebrary, Inc, Langley, E. J., & Knowles, R. B. (2012). Psychology of sadness. Nova Science Publishers.

Cita Chicago (17th ed.)

ebrary, Inc, Emile J. Langley, i Roger B. Knowles. Psychology of Sadness. New York: Nova Science Publishers, 2012.

Cita MLA (9th ed.)

ebrary, Inc, et al. Psychology of Sadness. Nova Science Publishers, 2012.