APA (7th ed.) Citation

Ruffin, R., & Gregory, P. R. (1993). Principles of economics (5th ed.). HarperCollins.

Chicago Style (17th ed.) Citation

Ruffin, Roy, and Paul R. Gregory. Principles of Economics. 5th ed. New York: HarperCollins, 1993.

MLA (9th ed.) Citation

Ruffin, Roy, and Paul R. Gregory. Principles of Economics. 5th ed. HarperCollins, 1993.

Warning: These citations may not always be 100% accurate.