The Four Chiefs. The four chiefs of the United Nations Postal Administration. Lithograph, 11x8 1/2 inches. Signed by Hirschfeld and numbered 340/500 in pencil, lower margin. 1991. Published by the United Nations in conjunction with a stamp issue commemorating the 40th anniversary of the United Nations Postal Administration. The four chiefs are Hugo Valdes, Anthony Fouracre, Riccarda Winter Tourou, and Rita Fernando. With the original documentation and a First Day of Issue envelope.