Dyfyniad APA

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

Dyfyniad Arddull Chicago

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

Dyfyniad MLA

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

Rhybudd: Mae'n bosib nad yw'r dyfyniadau hyn bob amser yn 100% cywir.