Roberto Ghiselli Ricci An Axiomatic Approach to a Class of Ranking Functions for Triangular Fuzzy Numbers. 155-172 1999 7 International Journal of Uncertainty, Fuzziness and Knowledge-Based Systems 2 http://dx.doi.org/10.1142/S0218488599000106 db/journals/ijufks/ijufks7.html#Ricci99