Cavanaugh, John C.
Cengage Learning, cop, 2015
Buku Teks SO
Lazarus, Richard S.
Oxford University Press, 2006
Buku Teks SO
editor, James E. Birren and K. Warner Schaie
Academic Press, 1990
Buku Referensi
K. Warner Schaie, Sherry L. Willis, editor ; Bob G. Knight, Becca Levy, Denise C. Park, associate editors
Elsevier, 2011
Buku Teks SO
Schultz, Richard
Prentice-Hall, 1999
Buku Teks SO