Sheet 32 Big Cairn GSGS 4231 First Edition 1942. Copied from map by South African Survey Coy SAEC 1941. Reproduced from 1:500,000 compilation of LRDG material, and surveys P A Clayton. GSGS 4231. Published WO 1942. Heliographed OS 1942. 1036/3/42, L.R. Egyptian "Purple" Grid.