1. Atchley, R. (2000). The social forces of aging. An introduction to social gerontology. Belmont, CA: Wadsworth Publishing.
2. Bagchi, A. (2005). The aging world. Lincoln, UK: iUniverse.
3. Barak, B. (2009). Age identity: A cross-cultural global approach. International Journal of Behavioral Development, 33, 2–11. http://dx.doi.org/10.1177/0165025408099485 .
4. Birren, J. E. (1996). Encyclopedia of gerontology. San Diego, CA: Academic.
5. Casey, B., & Yamada, A. (2002). Getting older, getting poorer? A study of the earnings, pensions, assets and living arrangements of older People in nine countries. Labour Market and Social (Policy Occasional Papers, No. 60). DEELSA/ELSA/WD (2002) 4. Paris: The Author.