Gaya APA
Principles of Economics. (1981).
Illinois:
Scott, Foresman And Company.
Gaya Chicago
Principles of Economics.
Ed. 2.
Illinois:
Scott, Foresman And Company,
1981.
.
Gaya MLA
Principles of Economics.
Ed. 2.
Illinois:
Scott, Foresman And Company,
1981.
.
Gaya Turabian
Principles of Economics.
Illinois:
Scott, Foresman And Company,
1981.
.