3Priya J. Wickramaratne, Myrna M. Weissman, Philip J. Leaf, Holford T.R. Age, period and cohort effects on the risk of major depression: results from five United States communities [J ]. Journal of clinical epidemiology, 1989, 42: 333-343.
4Barbara, Fredrickson. Positivity [M] . New York: Crown Publishers, 2009.
5Seligman M E P. Flourish: A Vi- sionary New Understanding of Happiness and Well-Being [M] . Free Press, 2011.