Outside Resources
Article: Harker and Keltner study of yearbook photographs and marriage http://psycnet.apa.org/journals/psp/80/1/112/
Article: Rich Lucas’s longitudinal study on the effects of marriage on happiness
http://psycnet.apa.org/journals/psp/84/3/527/
Article: Spending money on others promotes happiness. Elizabeth Dunn’s research
https://www.sciencemag.org/content/319/5870/1687.abstract
Article: What makes a life good?