GSGS (Series) ; 3868. 5th ed. "Air Survey by the R.A.F. and ground control by 2nd Colonial Survey Section, R.E., 1924-25. Field Revision by R.E. Survey Section, 1935-37. Plotted by the Geographical Section, General Staff, 1928-9. Drawn and heliographed at the Ordnance Survey 1929, 1939. Revised and reproduced by War Office, 1952." World polyconic projection.