1. L. V. Keldysh, Zh. Éksp. Teor. Fiz.,47, 1945 (1964).
2. A. D. Gladun and P. P. Barashev, Usp. Fiz. Nauk,98, 494 (1969).
3. R. Dech, Nonlinear Transformations of Random Processes [in Russian], Sovetskoe Radio, Moscow (1965), p. 66.
4. P. P. Zabreiko et al., Integral Equations [in Russian], Nauka, Moscow (1968).
5. A. P. Silin, Fiz. Tverd. Tela,12, 3553 (1970).