Gaya APA
The economic problem. (1968).
New Jersley:
prentice-hall.
Gaya Chicago
The economic problem.
1.
New Jersley:
prentice-hall,
1968.
Buku.
Gaya MLA
The economic problem.
1.
New Jersley:
prentice-hall,
1968.
Buku.
Gaya Turabian
The economic problem.
New Jersley:
prentice-hall,
1968.
Buku.