Guffey, Mary Ellen
Essentials of business communication
PWS-Kent, 1988
 Buku Teks
Guffey, Mary Ellen
Essentials of business communication
Cengage Learning Asia, 2008
 Buku Teks SO
Guffey, Mary Ellen
Essentials of business communication
PWS Publishing, 1991
 Buku Teks SO
Quible, Zone K.
Business Communication
Prentice Hall International,inc, 1996
 Buku Teks
Quible, Zone K.
Business Communication
Prentice-Hall International, 1996
 Koleksi Publik