[1] D. Dubois, H. Prade: 
Fuzzy numbers: An overview. In: Analysis of Fuzzy Information, CRC, Boca Raton, FA 1987, Vol. I, pp. 3-39. 
MR 0910312 | 
Zbl 0663.94028[2] M. Mareš: Algebra of fuzzy quantities. Internat. J. Gen. Systems 20 (1991), 1, 59-65.
[3] M. Mareš: 
Algebraic equivalences over fuzzy quantities. Kybernetika 29 (1993), 2, 121-132. 
MR 1227746[4] M. Mareš: 
Multiplication of fuzzy quantities. Kybernetika 28 (1992), 5, 337-356. 
MR 1197719[5] M. Mareš: 
Brief note on distributivity of triangular fuzzy quantities. Kybernetika 31 (1995), 5, 451-458. 
MR 1361306[6] M. Mareš: 
Additive decomposition of fuzzy quantities with finite supports. Fuzzy Sets and Systems 47 (1992), 341-346. 
MR 1166282