Gaya APA
ZIKMUND, W, G.
(1997).
Business research methods
(
5th ed.)
.
Philsdelphia:
The Dryden Press.
Gaya MLA
ZIKMUND, William, G..
"Business research methods".
5th ed.
Philsdelphia:
The Dryden Press,
1997.
Buku.