Schaie, K. W., & Willis, S. L. (1996). Adult development and aging (4th ed.). Harper Collins College.
Lua i Stíl Chicago (17ú heag.)Schaie, K. Warner, agus Sherry L. Willis. Adult Development and Aging. 4th ed. New York: Harper Collins College, 1996.
Lua MLA (9ú heag.)Schaie, K. Warner, agus Sherry L. Willis. Adult Development and Aging. 4th ed. Harper Collins College, 1996.
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