Παραπομπή APA

Keyfitz, N., & Flieger, W. (1990). World population growth and aging: Demographic trends in the late twentieth century. Chicago: University of Chicago Press.

Παραπομπή Chicago Style

Keyfitz, Nathan., and Wilhelm Flieger. World Population Growth and Aging: Demographic Trends in the Late Twentieth Century. Chicago: University of Chicago Press, 1990.

Παραπομπή MLA

Keyfitz, Nathan., and Wilhelm Flieger. World Population Growth and Aging: Demographic Trends in the Late Twentieth Century. Chicago: University of Chicago Press, 1990.

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