1. Henke Coll 1_204 Reference (shelfmark): Henke Coll 1_204 Title: United States of America Sixth International Philatelic Exhibition, Washington (SIPEX) Issue 5c stamp Scope & Content: Marginal block of four perforated MNH stamps with control number depicting an envelope. The stamp was designed by T. F. Naegele. Collection Area: Philatelic Collections Languages: English Date Range: 21 May 1966 Extent: 4 Items