APA (7th ed.) Citation

Ruffin, R. J., & Gregory, P. R. (1983). Principles of economics. Scott.

Chicago Style (17th ed.) Citation

Ruffin, Roy J., and Paul R. Gregory. Principles of Economics. Glenview, Ill: Scott, 1983.

MLA (9th ed.) Citation

Ruffin, Roy J., and Paul R. Gregory. Principles of Economics. Scott, 1983.