Rhodes, S., Richards, D.A., Ekers, D., McMillan, D., Byford, S., Farrand, P.A., Gilbody, S., Hollon, S.D., Kuyken, W., Martell, C., O'Mahen, H.A., O'Neill, E., Reed, N., Taylor, R.S., Watkins, E.R., Wright, K.A., "Cost and outcome of behavioural activation versus cognitive behaviour therapy for depression (COBRA): study protocol for a randomised controlled trial", Trials, 2014