Papalia, Diane E., author
Boston, 2007
Buku Teks
Santrock, John W., author
Wm. C. Brown Publishers, 1985
Buku Teks
Koncelik, Joseph A., author
Hutchinson Ross, 1982
Buku Teks
Kenney, Richard A.
Year Book Medical, 1982
Buku Teks
editor, James E. Birren and K. Warner Schaie
Academic Press, 1990
Buku Referensi