Nettle, D. (2005). Happiness: The science behind your smile. Oxford University Press.
Dyfyniad Arddull ChicagoNettle, Daniel. Happiness: The Science Behind Your Smile. Oxford, UK ; New York, N.Y.: Oxford University Press, 2005.
Dyfyniad MLANettle, Daniel. Happiness: The Science Behind Your Smile. Oxford University Press, 2005.
Rhybudd: Mae'n bosib nad yw'r dyfyniadau hyn bob amser yn 100% cywir.