1. Bard, J.: Optimality conditions for the bi-level programming problem. Nav. Res. Logist. Q. Res. 31, 13–26 (1984)
2. Bard, J.: Practical Bi-level Optimization, Algorithms and Applications. Kluver Academic, Dordrecht (1988)
3. Behera, S.K., Nayak, J.R.: Optimal solution of fuzzy nonlinear programming problems with linear constraints. Int. J. Adv. Sci. Technol. 4(2), 43–92 (2012)
4. Bellman, R.E., Zadeh, L.A.: Decision making in a fuzzy environment. Manag. Sci. 17(4), 141–164 (1970)
5. Chen, Y-F., Wang, F-S.: Crisp and fuzzy optimization of a fed-batch fermentation for ethanol production. Ind. Eng. Chem. Res. 42, 6843–6850 (2003)