1. Benfante, R., Reed, D., and Brody, J., 1985, Biological and social predictors of health in an aging cohort, J. Chron. Dis. 38: 385–395.
2. Busse, E. W., and Maddox, G. L., 1985, The Duke Longitudinal Studies of Normal Aging. 1955–1980. Springer, New York.
3. Callahan, D., 1987, Setting Limits. Medical Goals in an Aging Society. Simon & Schuster, New York.
4. Campbell, R. T., 1986, Longitudinal design and longitudinal analysis. A comparison of three approaches, Res. Aging 8: 480–502.
5. Committee on an Aging Society, 1985, America’s Aging. Health in an Older Society. Institute of Medicine/National Research Council, National Academy Press, Washington, D. C.