Gaya APA
Guffey, M, E., Bertha, D.
(2010).
Essentials of Business Communication
(
2)
.
Singapore:
Cengage Learning.
Gaya MLA
Guffey, Mary, Ellen., Bertha, Du-Babcock.
"Essentials of Business Communication".
2
Singapore:
Cengage Learning,
2010.
Texts.