1. Beiträge zur Begründung der transfiniten Mengenlehre;Cantor;Math. Ann.,1895
2. L-fuzzy sets;Goguen;J. Math. Anal. Appl.,1967
3. Category of V-sets;Goguen;Bull. Amer. Math. Soc.,1969
4. Concept representation in natural and artificial languages;Goguen;Internat. J. Man-Machine Stud.,1974
5. A. Kaufmann, Introduction to the Theory of Fuzzy Subsets, vol. I, Academic Press, New York, 1975.