Ruffin, R., & Gregory, P. R. (1993). Principles of economics (5th ed.). HarperCollins.
Chicago Style (17th ed.) CitationRuffin, Roy, and Paul R. Gregory. Principles of Economics. 5th ed. New York: HarperCollins, 1993.
MLA (9th ed.) CitationRuffin, Roy, and Paul R. Gregory. Principles of Economics. 5th ed. HarperCollins, 1993.
Warning: These citations may not always be 100% accurate.