Russian alphabet - Wikipedia
https://en.wikipedia.org/wiki/Russian_alphabet50 rader · The Russian alphabet (Russian: ру́сский алфави́т, tr. russkiy alfavit, IPA: [ˈruskʲɪj ɐlfɐˈvʲit] or, more traditionally, Russian: ру́сская а́збука, tr. russkaya azbuka, IPA: [ˈruskəjə ˈazbʊkə]) was derived from Cyrillic script for Old Church Slavonic language. Initially an old variant of the Bulgarian alphabet, it became used in the Kievan Rus' since ...
U (Cyrillic) - Wikipedia
https://en.wikipedia.org/wiki/U_(Cyrillic)Historically, Cyrillic U evolved as a specifically East Slavic short form of the digraph ⟨оу⟩ used in ancient Slavic texts to represent /u/. The digraph was itself a direct loan from the Greek alphabet, where the combination ⟨ου⟩ (omicron-upsilon) was also used to represent /u/. Later, the o was removed, leaving the modern upsilon-only form. Consequently, the form of the letter is derived from Greek upsilon⟨Υ υ⟩, which was parallelly also …