Mechanism of action in CBT (MAC): methods of a multi-center randomized controlled trial in 369 patients with panic disorder and agoraphobia. - Gloster, A. T.; Wittchen, H. U.; Einsle, F.; Höfler, M.; Lang, T.; Helbig-Lang, S.; Fydrich, T.; Fehm, L.; Hamm, A. O.; Richter, J.; Alpers, G. W.; Gerlach, A. L.; et al. (European Archives of Psychiatry & Clinical Neuroscience, 2009)