1. Inst. Org. i Zarz. Politechniki Wr., Report No. 34;S Chanas,1988
2. Gass, S.J. (1969) Linear Programming — Methods and Applications, McGraw-Hill Book Company, New York.
3. Yager, R.R. (1986)‘Expected values from probabilities of fuzzy subsets’, European Journal of Operational Research 25, 336–344.
4. Zadeh, L.A. (1979) ‘Fuzzy sets and information granuality’, in M.M. Gupta, R.K., Ragade and R.R. Yager (eds),.Advance in Fuzzy Set Theory and Application, North-Holland Publ. Company, pp. 3–18
5. Zadeh, L.A. (1973) The Concept of a Linguistic Variable and its Application to Approximate Reasoning, American Elsvier Publ. Company, New York.