APA (7th ed.) Citation

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

Chicago Style (17th ed.) Citation

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

MLA (8th ed.) Citation

Emmons, Robert A., and Michael E. McCullough. The Psychology of Gratitude. Oxford University Press, 2004.