Introduction to the theory of fuzzy subsets 
Kaufmann, A.(Arnold),1911-
Swanson, D. L.
New York London Academic Press,
1975
In 3 vols
Translation of: 'Introduction à la théorie des sous-ensembles flous à l'usage des ingénieurs'. Paris : Masson, 1973-
Bibliography: p.403-409. - Includes index
Set theory.