German silver lever pocket watch with centre seconds Circa 1952

Silver open faced lever watch by A.Lange & Söhne 
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A German rare silver open faced centre seconds german military observation pocket watch with A. Lange & Söhne certificate, circa 1952. Sold 16.10.1952 for 430 DM. Cal.48 frosted gilt manual wind lever movement numbered 217431, with cut and compensated bimetallic balance, swan-neck micro regulation.
Black dial with luminous Roman numerals and outer five-minute batons, blued steel and luminous hands, case with snap-on back and numbered, together with a recent A. Lange & Söhne certificate and a copy of the original order ledger, case and movement signed.
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Diameter: 59 mm
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Signed: A. Lange & Söhne Glashütte S.A.