MLA

Carr, Alan. Positive Psychology : the Science of Happiness and Human Strengths. 2nd ed. London: Routledge, 2011.

APA

Carr, A. (2011). Positive psychology : the science of happiness and human strengths. 2nd ed. London: Routledge.

Chicago

Carr, Alan, Positive Psychology: The Science of Happiness and Human Strengths. 2nd ed. London: Routledge, 2011.