Ruffin, R. J. (1988). Principles of microeconomics (3ª ed.). Scott, Foresman.
Cita Chicago (17th ed.)Ruffin, Roy J. Principles of Microeconomics. 3ª ed. Scott, Foresman, 1988.
Cita MLA (9th ed.)Ruffin, Roy J. Principles of Microeconomics. 3ª ed. Scott, Foresman, 1988.
Atenció: Aquestes cites poden no estar 100% correctes.