APA Format
Samuelson, Paul A.; Nordhaus, William D.. (1989).
Economics / Paul A. Samuelson, William D. Nordhaus
. New York :: McGraw-Hill Book Company,.
MLA Format
Samuelson, Paul A.; Nordhaus, William D..
Economics / Paul A. Samuelson, William D. Nordhaus
. New York :: McGraw-Hill Book Company,, 1989
Chicago Format
Samuelson, Paul A.; Nordhaus, William D.. Economics / Paul A. Samuelson, William D. Nordhaus. New York :: McGraw-Hill Book Company,, 1989.