Gaya APA
Samuelson, Paul A., Nordhaus, William D.. (1989).
Economics (13th ed.).
New York:
McGraw-Hill.
Gaya Chicago
Samuelson, Paul A., Nordhaus, William D..
Economics.
13th ed.
New York:
McGraw-Hill,
1989.
Text.
Gaya MLA
Samuelson, Paul A., Nordhaus, William D..
Economics.
13th ed.
New York:
McGraw-Hill,
1989.
Text.
Gaya Turabian
Samuelson, Paul A., Nordhaus, William D..
Economics.
13th ed.
New York:
McGraw-Hill,
1989.
Print.