Fearnside, W. Ward, author
Prentice-Hall, 1997
Buku Teks
Johnson, Donald M., author
Harper and Row, 1972
Buku Teks
Bruner, Jerome, author
John Wiley & Sons, 1956
Buku Teks
Ennis, Robert H.
Prentice-Hall, 1996
Buku Teks
Salmon, Merrilee H., author
Wadsworth, 2013
Buku Teks