Twomey, David P.
South-Western Publishing Company, 1986
Buku Teks
Pitt, Gwyneth, author
Sweet & Maxwell, 2011
Buku Teks
Player, Macka
West Publishing, 1992
Buku Teks
McDonald, Janis L., author
Pearson/Prentice Hall, 2006
Buku Teks
Bennet-Alexander, Dawn, author
Irwin/McGraw-Hill, 2004
Buku Teks