MITAU (Latvia): 10 kopeck brown & blue, large margins, tied by clear pre-philatelic single line "MITAVA" to entire letter to Moscow, with reverse side arrival mark of March 1858. The stamp tiny penstroke at left; some minor ageing and small part of backflap restored, still very fine and rare; most likely the finest of 4 covers recorded with this cancellation. Certificate Buchsbayew (2015)