Guffey, Mary Ellen
Essentials of business communication
PWS Publishing, 1991
 Buku Teks
Guffey, Mary Ellen
Essentials of business communication
PWS-Kent, 1988
 Buku Teks
Quible, Zone K.
Business Communication
Prentice Hall International,inc, 1996
 Buku Teks
Quible, Zone K.
Business Communication
Prentice Hall International,inc, 1996
 Koleksi Publik
Ewald, Helen Rothschild
Business communication
Prentice Hall International, 1997
 Buku Teks