Gesell, Arnold, author
Harper & Row, 1949
Buku Teks
Keenan, Thomas, author
Sage Publications, 2004
Buku Teks
Hetherington, Mavis E.
McGraw-Hill , 2006
Multimedia
William Damon, editor-in-chief
John Wiley & Sons, 1998
Buku Referensi
New York, 1993
Buku Teks