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SUDAN - OFFICIALS POSTMARK & VARIETIES SPECIALISTS COLLECTION. 1902 Quatrefoil Wmk 'O.S.G.S.' overprinted 1m brown & pink 'Arab Postman' selection on two sleeved Exhibition pages. Includes a choice group of Khartoum, Wadi Halfa & Halfa cancelled examples, eight stamps bearing 'Round Stops' varieties, an 'Oval O' example with Photo Certificated and two examples of Forged overprints for reference. An interesting Specialized collection (24 stamps)