1. Sur des operations definies pour des nombres réels;Aczél;Bull. Soc. Math. France,1949
2. Sur les measures du degré de flou;Alsina;Stochastica,1979
3. Fuzzy cardinality and the modeling of imprecise quantification;Dubois;Fuzzy Sets and Systems,1985
4. On cardinality and singular fuzzy sets;Dyczkowski,2001
5. On measures of fuzziness and their representations;Ebanks;J. Math. Anal. Appl.,1983