[1] Bellman R. E., Zadeh L. A. (1970) " Decision making in a fuzzy environment '', Management Sciences, 17, 141-164.
		                                                                                        			                                                		[2] Campos L., Verdegay J. L. (1989) " Linear programming problems and ranking of fuzzy numbers '', Fuzzy Set and Systems, Elsevier Science Publishers, 32, 1-11.
		                                                                                        			                                                		[3] Ebrahimnejad A., Nasseri Sh., Lotfi F. H., Soltanifar M. (2010) " A primal- dual method for linear programming problems with fuzzy variables '', European Journal of Industrial Engineering, 4, 189-209.
		                                                                                        			                                                		[4] Ganesan K., Veeramani P. (2006) " Fuzzy linear programs with trapezoidal fuzzy numbers '', Annals Of Operation Research-incl, 143, 305-315.
		                                                                                        			                                                		[5] Jahanshahloo Gh. (2003) " Operations research 2 '', Pnu, 74, Tehran.
		                                                                                        			                                                		[6] Liou T. S., Wang M. J. (1992) " Ranking fuzzy numbers with integral value '', Fuzzy Sets and Systems, Elsevier Science Publishers, 50, 247-255.
		                                                                                        			                                                		[7] Maleki H. R.  (2002) " Ranking function and their application to fuzzy linear programming '', Far East Journal of Mathematics Sciences, 4, 283-301.
		                                                                                        			                                                		[8] Maleki H. R., Tata M., Mashinchi M. (2000) " Linear programming with fuzzy variables '', Fuzzy Set and System, Elsevier Science Publishers, 109, 21-33.
		                                                                                        			                                                		[9] Tanaka H., Okada T., Asai K. (1973) " On fuzzy mathematical programming '', Journal of Cybernetics Systems, 3, 37-46.
		                                                                                        			                                                		[10] Zimmerman H. J. (1978) " Fuzzy programming and linear programming with several objective function '', Fuzzy Set and Systems, Elsevier Science Publishers, 1, 45-55.