4Battese, G. E. and T. J. Coelli. Frontier Production Functions, Technical Ef?ciency and Panel Data: With Application to Paddy Farmers in India [ J ]. Journal of Productivity Analysis, 1992( 3): 153-169.
5Kodde D. and F. Palm. Wald Criteria for Jointly Testing Equality and Inequality Ristrictions [J ]. Econometrica, 1986 (54): 1243-1248.