Publications International, 2000
Buku Referensi
Hilliard, Brooks L., author
Dow Jones-Irwin , 1984
Buku Teks SO
Gookin, Dan
IDG Books, 1995
Buku Teks
Solomon, Michael R., author
Pearson - Prentice Hall, 2009
Buku Teks
Solomon, Michael R., author
Allyn and Bacon, 1994
Buku Teks