Churchill, R., Hunot, V., Corney, R., Knapp, M., McGuire, H., Tylee, A. and Wessely, S. (2002) A systematic review of controlled trials of the effectiveness and cost-effectiveness of brief psychological treatments for depression. Health Technology Assessment, 5 (35). pp. 1-173. ISSN 1366-5278 (doi:10.3310/hta5350)