APA (7th ed.) Citation

Ruffin, R. ., & Gregory, P. R. (1997). Principles of economics (6th ed.). Addison-Wesley.

Chicago Style (17th ed.) Citation

Ruffin, Roy , and Paul R. Gregory. Principles of Economics. 6th ed. Reading, Mass.: Addison-Wesley, 1997.

MLA (9th ed.) Citation

Ruffin, Roy , and Paul R. Gregory. Principles of Economics. 6th ed. Addison-Wesley, 1997.