Letters UPU + other issues

Quality: MIX

N° 880 '80c. van Tassis', 13th Congress of the U.P.U. in Brussels, study collection with 6 letters/PWST (including the "Beneluksa Esperanto - Kongres Antwerpen" from 23:25 May 1953), the 4 plate numbers, some cancelled stamps, nice item, vf