Bockting, C. L. H., Schene, A. H., Spinhoven, P., Koeter, M. W. J., Wouters, L. F. J. M., Huyser, J., & Kamphuis, J. H. (2005). Preventing relapse in recurrent depression using cognitive group therapy: A randomized controlled trial. Journal of consulting and clinical psychology, 4, 647-657.