Knight, J., & Gunatilaka, R. (2009). Is Happiness Infectious? Department of Economics (University of Oxford).
Lua i Stíl Chicago (17ú heag.)Knight, J., agus R. Gunatilaka. Is Happiness Infectious? Department of Economics (University of Oxford), 2009.
Lua MLA (9ú heag.)Knight, J., agus R. Gunatilaka. Is Happiness Infectious? Department of Economics (University of Oxford), 2009.
Rabhadh: Seans nach mbeach na luanna seo go hiomlán cruinn i ngach uile chás.