Salvatore, Dominick, author
McGraw-Hill, 1996
Buku Teks
edited by Lorraine Eden
St. Martin's Press, 1993
Buku Teks
Warde, Ibrahim, author
Edinburgh University Press, 2000
Buku Teks
Salvatore, Dominick, author
McGraw-Hill, 1993
Buku Teks
Vernon-Wortzel, Heidi, author
John Wiley & Sons, 1997
Buku Teks