1. Kolmogorov A.N. On analytical methods in probability theory. Uspekhi Mat. Nauk 1938, 5, 5-41. (in Russian)
  2. Portenko N.I. Generalized diffusion processes. In: Translations of Mathematical Monographs, 83. Amer. Math. Soc., 1990.
  3. PortenkoM.I. Diffusion processes in media with membranes. In: Samoilenko A.M. (Ed.) Proc. Inst.Math., 10. Institute of Mathematics of NAS of Ukarine, Kyiv, 1995. (in Ukrainian)
  4. Al Farah H., Portenko M. Limit theorem for the number of level crossings of a fixed weakly convergent sequence of diffusion processes. Institute of mathematics of NAS of Ukarine, Kyiv, 2007. (in Ukrainian)
  5. Dynkin E.B. Markov Processes. Springer, Berlin, Heidelberg, 1965.