Unützer, J., Katon, W., Callahan, C. M., Williams, J. W., Jr., Hunkeler, E., Harpole, L., Hoffing, M., Penna, R. D. D., Noel, P. H., Lin, E. H. B., Tang, L., & Oishi, S. (2003). Depression treatment in a sample of 1,801 depressed older adults in primary care. Journal of the American Geriatrics Society, 51(4), 505–514. DOI: 10.1046/j.1532-5415.2003.51159.x