Gaya APA
Principles of economics. (2008).
Canada:
South Western Cengage Learning.
Gaya Chicago
Principles of economics.
5.
Canada:
South Western Cengage Learning,
2008.
Buku.
Gaya MLA
Principles of economics.
5.
Canada:
South Western Cengage Learning,
2008.
Buku.
Gaya Turabian
Principles of economics.
Canada:
South Western Cengage Learning,
2008.
Buku.