1. B. De Baets, R. Mesiar, Metrics and T-equalities, J. Math. Anal. Appl., 267 (2002) 531–547.
2. Pseudo-metrics and T-equivalences;De Baets;J. Fuzzy Math.,1997
3. M. De Cock, E.E. Kerre, On (un)suitable fuzzy relations to model approximate equality, Fuzzy Sets and Systems 133 (2) (2003), this issue.
4. M. De Cock, E.E. Kerre, Approximate equality is no fuzzy equality, in: Proceedings of the 2nd International Conference on Fuzzy Logic and Technology (EUSFLAT 2001), Leicester, UK, September 2001, pp. 369–371.
5. The Poincaré paradox and non-classical logics;Höhle,1999