From NC:

 

“In 1929, the famous Russian linguist M.N. Speransky published a mysterious inscription of nine lines, which he found on the flyleaf – a sheet next to the binding – books of the XVII century. The scientist considered the inscription “totally unbreakable”: there were Cyrillic letters in the record, but they alternated with some obscure signs >> [425]. It turns out that “mysterious signs are in the cipher of Russian diplomatic documents, in the inscription (425 letters) on the Zvenigorod bell, cast under Alexey Mikhailovich in the XVII century, in the Novgorod secret writing of the XIV century, in Serbian cryptograms … Particularly curious are the parallel combinations of mysterious monograms with Greek the inscriptions on the coins of an earlier time … Many of the same outlines were found in the ruins of ancient Greek cities – colonies in the Black Sea region.”