274th - 283th Corinphila Auction - Day 4

1882: 5 st. yellow green and pale green, nine examples consisting of four pairs and a single on reverse of 1888 registered letter tied by blue Sistov bilingual single circle datestamp (May 27) to Sofia. The letter is endorsed "contains one key" explaining the second weight rate, which together with the registration makes the letter correctly franked at 45 stotinki. Opinion Penev (2021).