4) H. Tanaka, T. Shimomura, J. Watada and K. Asai: Fuzzy Linear Regression Analysis of the Number of Staff in Local Government, FIP-84 at Kauai, Hawaii (1984)
5) L.A. Zadeh: The Concept of a Linguistic Variable and Its Application to Approximate Reasoning-I, Inform. Sci., 8, 199/249 (1975)