Miller, Roger LeRoy, author
West Educational Publishing, 1999
Buku Teks
Barnes, A. James, author
Homewood, Ill., Learning Systems
Buku Teks
Carvan, John
LBC Information Service, 1997
Buku Teks
Woon, Walter C. M., author
Prentice-Hall, 2000
Buku Teks
Holmes, Ann
Cavendish Publishing Limited, 1997
Buku Teks