3Ottmar RoehM and Stephan Dabbert,Integrating Agri-Environmental Programs into Regional Production Models:an Extension of Positive MathematicalProgramming,Amer.J.Agr.Eeon.85(1),February 2003:254~265
4Richard E.Howitt,Positive Mathematical Programming,Amer.J.Agri.Econ.77 May 1995:329~342
5Thomas Heckelei,Wolfgan Bfitz.Models Based on Positive Mathematical Programming:State of the Art and Further Extensions