Kell’ onni on … Lyubomirsky Sonja, King Laur Diener Ed The Benefits of Frequent Positive Affect: Does Happiness Lead to Success. Ps Bull 2005:131: 803-855. Pressman Sarah D, Cohen Sheldon Does Positive Affect Influence Health? Ps Bull 2005:131: 925-971.

Vilkkumaa, I. (2006). Kell’ onni on … Lyubomirsky Sonja, King Laur Diener Ed The Benefits of Frequent Positive Affect: Does Happiness Lead to Success. Ps Bull 2005:131: 803-855. Pressman Sarah D, Cohen Sheldon Does Positive Affect Influence Health? Ps Bull 2005:131: 925-971. Sosiaalilääketieteellinen Aikakauslehti, 43(1). Retrieved from https://journal.fi/sla/article/view/2362