PratsiovytyiM. V.; TorbinH. M. Superfractality of the set of numbers having no frequency of<em class="a-plus-plus">n</em&gt;-adic digits, and fractal probability distributions. Ukrains’kyi Matematychnyi Zhurnal, v. 47, n. 7, p. 971–975, 25 Jul. 1995.