We used to know how to get together and really let our hair down. Then, in the early 1600s, a mass epidemic of depression broke out - and we've been living with it ever since. Something went wrong, but what? Barbara Ehrenreich unpicks the causes of our unhappiness
M. Hu, E. Lim, A. Sun, H. Lauw, and B. Vuong. Proceedings of the sixteenth ACM conference on Conference on information and knowledge management, page 243--252. New York, NY, USA, ACM, (2007)