1. H. N. Watson, Theory of Bessel Functions [Russian translation], Part 1, IL (1949).
2. S. Chandrasekar, Stochastic Problems in Physics and Astronomy [Russian translation], IL (1947).
3. B. R. Levin, Theory of Stochastic Processes and Its Application to Radio Engineering [in Russian], Sovetskoe Radio (1960).
4. A. Sommerfeld, Partial Differential Equations of Physics [Russian translation], IL (1950).
5. V. A. Fok, Dokl. Akad. Nauk SSSR,39, 279 (1943).