Gaya APA
Backstrom, C, H., Hursh, G, D.
(1981).
Survey Research
.
U.S.A:
John Wiley \r Son.
Gaya MLA
Backstrom, Charles, H.., Hursh, Gerald, D..
"Survey Research".
U.S.A:
John Wiley \r Son,
1981.
print.