Mayer, K. U., Baltes, P. B., Baltes, M. M., Borchelt, M., Delius, J. A. M., Helmchen, H., et al. (1999). What do we know about old age and aging? Conclusions from the Berlin Aging Study. In P. B. Baltes, & K. U. Mayer (Eds.), The Berlin Aging Study: Aging from 70 to 100 (pp. 475-519). Cambridge: Cambridge University Press.