GSGS series 4414. Sheet 3310, Second Edition (A.E.F.). First edition copied from German Topographische Karte 1:25,000 Sheet 3310 dated 1936 and photolithograpged by the British Ordnance Survey in 1943. Second edition revised from air photographs October 1944 by 21 A. Gp Air Survey Group. Lambert modified conical orthomorphic projection. Nord de Guerre Grid.