FRENCH CONGO, 1900, 15c on 30c BROWN ON BISTER - BLUE SURCHARGE - USED, #51, Brazzavile d.s., few bit shortish perfs., fine-very fine, rare and seldom offered, signed A Brun and Scheller, with 2018 Scheller cert., cat. $2,600.00, Maury #26 @ €3,350.00