Walter A. Elwell, general editor
Baker Book House, 1995
Buku Referensi
Dubin, rese P
Prentice Hall Press, 1999
Buku Teks SO
Hauer, Christian E.
Prentice-Hall, 1998
Buku Teks SO
Missler, Chuck
Visimedia, 2006
Buku Teks SO
Keene, Michael
Kanisius, 2006
Buku Teks SO