Chernobay S.L. Prussian diary of the artist O.Y. Klever (November 26, 1942 – December 27, 1943)Based on the study of the diary of the Great Patriotic War period, stored in the Central State Archive of Literature and Arts of St. Petersburg, of the talented painter, theater artist and book illustrator O.Y. Klever, who was repatriated to Germany as a Volksdeutsche, placed in a camp on the territory of East Prussia and returned to the USSR in 1946, the source possibilities of this unique document are revealed.