Dyfyniad APA
Samuelson, P. A., & Nordhaus, W. D. (1989). Economics (13th ed.). McGraw-Hill Book.
Dyfyniad Arddull Chicago
Samuelson, Paul A., and William D. Nordhaus. Economics. 13th ed. New York: McGraw-Hill Book, 1989.
Dyfyniad MLA
Samuelson, Paul A., and William D. Nordhaus. Economics. 13th ed. McGraw-Hill Book, 1989.
Rhybudd: Mae'n bosib nad yw'r dyfyniadau hyn bob amser yn 100% cywir.