1. Averkin, A.N., Nechetkie mnozhestva v modelyakh upravleniya i iskusstvennogo intellekta (Fuzzy Sets in Models of Control and Artificial Intelligence), Moscow: Nauka, 1986.
2. Pegat, A., Nechetkoe modelirovanie i upravlenie (Fuzzy Modeling and Control), Moscow: BINOM. Laboratoriya Znanii, 2015.
3. Puri, M.L. and Ralescu, D.A., Fuzzy Random Variables, J. Math. Anal. Appl., 1978, vol. 64, pp. 409–422.
4. Feng, Y., Hu, L., and Shu, H., The Variance and Covariance of Fuzzy Random Variables, Fuzzy Sets Syst., 2001, vol. 120, no. 2, pp. 487–497. https://doi.org/10.1016/S0165-0114(99)00060-3
5. Shvedov, A.S., Estimating the Means and Covariances of Fuzzy Random Variables, Applied
Econometrics, 2016, vol. 42, pp. 121–138.