Oxford University Press, 2005
Buku Teks
Asch, David, author
Crest Publishing House, 1999
Buku Referensi
Speser, Phyllis L., author
John Wiley & Sons, 2006
Buku Teks
Lyman, Michael D., author
Pearson/Prentice Hall, 2005
Buku Teks
Bishop, Matt, author
Addison-Wesley, 2003
Buku Teks