Kwa maelezo zaidi, tazama N. Gregory Mankiw, Macroeconomics, toleo la nne (New York, NY: Worth Publishers, 2000), pp. 90-97, au Olivier Blanchard, Macroeconomics, toleo la pili (Upper Saddle River, NJ: Prentice Hall, 2000), pp. 214-220.
Kuna majadiliano ya kina zaidi katika Macroeconomics, Toleo la Nne.