Generalized Method of Moment (GMM) estimation is one of two developments in econometrics in the 80ies that revolutionized empirical work in macroeconomics. (The other being the understanding of unit roots and cointegration.) The path breaking articles on GMM were those of Hansen (1982) and Hansen and Singleton (1982). For introductions to GMM, Davidson and MacKinnon (1993) have comprehensive ch...