Gaya APA

Hefferon, K., Boniwell, I. (2011). Positive Psychology : Theory, Research and Aplications . New York: Mc GrawHill.

Gaya MLA

Hefferon, Kate., Boniwell, Ilona. "Positive Psychology : Theory, Research and Aplications". New York: Mc GrawHill, 2011. Elektronik/Digital.