Bromet, E., Andrade, L.H., Hwang, I., Sampson, N.A., Alonso, J., Girolamo, G., … Kessler, R.C., (2011). Cross-national epidemiology of DSM-IV major depressive episode. BMC Medicine, 9(90), 1-16. doi:10.1186/1741-7015-9-90