GSGS series 4414. Sheet 2509, Second Edition (A.E.F.). Copied from German Topographische Karte 1:25,000 Sheet 2509 dated 1936 and photolithographed by the British Ordnance Survey in 1944. Revised from air photos December, 1944 (I RCE). Lambert modified conical orthomorphic projection. Nord de Guerre Grid.