AMS series M841. Sheet 4102, Third Edition (A.E.F.). Copied from Netherland Topografische Inrichting 1:25,000 dated 1931-38 and Topografische Inrichting 1:50,000 dated 1927-39. Revised from air photographs from 1940, 1942 and 1943 in December 1944 by 21 A.Gp. Air Survey Group. Polyconic projection. Contour interval at 10 metres. Nord de Guerre Grid.