Gaya APA
Sirait, C, B., Sirait, B.
(2015).
Public Speaking and Business
.
Jakarta:
PT Elex Media Komputindo.
Gaya MLA
Sirait, Charles, Bonar., Sirait, Bunga.
"Public Speaking and Business".
Jakarta:
PT Elex Media Komputindo,
2015.
Text.