Levitt, S. D. (2009). Freakonomics. Harper Collins.
Cita Chicago (17th ed.)Levitt, Steven D. Freakonomics. Harper Collins, 2009.
Cita MLA (9th ed.)Levitt, Steven D. Freakonomics. Harper Collins, 2009.
Atenció: Aquestes cites poden no estar 100% correctes.