Lindenberger, Ulmann, Reiner Gilberg, Todd D. Little, Reinhard Nuthmann, Ulrich Pötter & Paul B. Baltes (1999). Sample selectivity and generalizability of the results of the Berlin Aging Study. In: Paul B. Baltes & Karl Ulrich Mayer (eds.). The Berlin Aging Study: Aging from 70 to 100. New York: Cambridge University Press: 56-82