His Crimean campaign is mentioned in only one source, the Russian version of the Life of St. Stephen of Sougdaia (Stephen of Surozh in Russian), tentatively dated to the 15th or 16th centuries.
His Crimean expedition is referenced solely in one document, the Russian version of the Life of St. Stephen of Sougdaia (Stephen of Surozh), which is approximately from the 14th to the 16th century.