AMS series M841. Sheet 3508, Second Edition (A.E.F.). Copied from Netherland Topografische Inrichting 1:25,000 dated 1935 and Topografische Inrichting 1:50,000 dated 1927. Revised from air photographs from 1943 in October 1944 by the 21 A.Gp. Air Survey Group. Polyconic projection. Contour interval at 10 metres. Nord de Guerre Grid.