“…Later various models (the Fermi-Ulam model and others, see, e.g. [Brahic, 1971;Lichtenberg & Lieberman, 1990;Lichtenberg et al, 1980;Pustyl'nikov, 1987Pustyl'nikov, , 1994Pustyl'nikov, , 1995Pustyl'nikov et al, 1995;Ulam, 1961;Zaslavsky, 1970]) have been developed which explained this phenomenon to a certain extent.…”