Cita APA (7th ed.)

ebrary, Inc, Emmons, R. A., & McCullough, M. E. (2004). The psychology of gratitude. Oxford University Press.

Cita Chicago (17th ed.)

ebrary, Inc, Robert A. Emmons, i Michael E. McCullough. The Psychology of Gratitude. Oxford ; New York: Oxford University Press, 2004.

Cita MLA (9th ed.)

ebrary, Inc, et al. The Psychology of Gratitude. Oxford University Press, 2004.