APA (7th ed.) Citation

Layard, P. R. G. (2005). Happiness: Lessons from a new science. Penguin Press.

Chicago Style (17th ed.) Citation

Layard, P. R. G. Happiness: Lessons from a New Science. New York: Penguin Press, 2005.

MLA (8th ed.) Citation

Layard, P. R. G. Happiness: Lessons from a New Science. Penguin Press, 2005.