Cita APA (7th ed.)

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

Cita Chicago (17th ed.)

Ruffin, Roy J., i Paul R. Gregory. Principles of Economics. Glenview, Il: Scott, 1983.

Cita MLA (9th ed.)

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