Samuelson, P. A., & Nordhaus, W. D. (1980). Economics (11th ed.). McGraw-Hill.
Cita Chicago (17th ed.)Samuelson, Paul A., i William D. Nordhaus. Economics. 11th ed. New York: McGraw-Hill, 1980.
Cita MLA (9th ed.)Samuelson, Paul A., i William D. Nordhaus. Economics. 11th ed. McGraw-Hill, 1980.
Atenció: Aquestes cites poden no estar 100% correctes.