Couso, I. ., & Sánchez, L. . (2008). Higher order models for fuzzy random variables. Fuzzy Sets and Systems, 159, 237-258. https://doi.org/10.1016/j.fss.2007.09.004
Sánchez, L. . (1998). A random sets-based method for identifying fuzzy models. Fuzzy Sets and Systems, 98, 343-354. https://doi.org/10.1016/S0165-0114(97)00010-9