1. V. P. Maslov, Complex Markov Chains and Feynman Integrals for Nonlinear Systems (Nauka, Moscow, 1976) [in Russian].
2. S. Albeverio and R. Hoegh-Krohn, Mathematical Theory of Feynman Path Integrals (Springer-Verlag, Berlin, 1976).
3. O. G. Smolyanov and E. T. Shavgulidze, Path Integrals (Mosk. Gos. Univ., Moscow, 1990) [in Russian].
4. P. R. Chernoff, J. Funct. Anal. 84, 238–242 (1968).
5. I. M. Gel’fand and A. M. Yaglom, Usp. Mat. Nauk 11(11), 77–114 (1956).