A reader writes, "Someone was nice enough to scan the pages of a Cyrillic alphabet book from the 1930's. The book encouraged adult literacy through erotic drawings of figures in various acts of copulation. Note: flying penises, lesbian acts and cloven hoofed demons appear. Male homosexual acts, do not."

These images are obviously NSFK (not safe for Kremlin). The artist was Sergei Merkurov, who went on to become a People's Artist of the USSR. As the accompanying text notes, it's a fascinating look at the libertine sexuality of the pre-Stalinist period.

Update: Ross Wolfe comments, "There actually are a couple male homosexual acts in the Soviet erotic alphabet. Specifically, these occur in the letters Й and З, though you have to pay close attention. And the latter is potentially even more scandalous, with a small satyr fucking what looks to be either a young boy or dwarf from behind. No penis is actually shown, but the short hair and lack of tits suggest its masculinity."

Soviet-era erotic alphabet book from 1931 [Советская эротическая азбука 1931 года]