The equation ΔMV is equal to ΔPQ while real GDP (which is adjusted for inflation), is fixed is a modern method to distinguish: (w) Adam Smith’s labor theory of value. (x) Francois Quesnay’s circular flow model. (y) Roberto Michaels’ Iron Law of Oligarchy. (z) David Hume’s Price Specie-Flow Mechanism that is an early version of the Quantity Theory of Money].