GSGS (Series) ; 3868. 2nd ed. "Minor corrections 1939. (Grid change only, 1945.)" "Compiled by the Geographical Section, General Staff, 1929. Field Revision by R.E. Survey Section, 1935-37. Drawn and heliographed at the Ordnance Survey 1929, 1939. Photolithographed by O.S. 1945." World polyconic projection.