United States. Army Map Service. North Decimal Degree 42.0000. South Decimal Degree 41.0000. East Decimal Degree -8.0000. West Decimal Degree -9.0000. Alternate title: Porto, Portugal. Polyconic projection. With Portuguese-English glossary. Relief shown by 100 m. contour interval, gradient tint and spot heights. Standard map series designation: A.M.S. M581. "Compiled from Portugal, 1:50,000, Instituto Geografico, 1902-40; Portugal, 1:100,000, Servicos Geodesicos, sheets 4 and 5, 1895-99; Portugal, 1:250,000, Estador Maior do Exercito, 1937-38; Spain 1:200,000, Cuartel General del Generalisimo, sheets 21 and 22, 1901; Iberian Peninsula, 1:250,000, GSGS, sheets S1272 and S2472, 1941; Spain and Portugal Road Map, 1:400,000, AMS, sheets 41 and 44, Third Edition, 1943; Railways in Spain and Portugal 1:1,500,000, GSGS, 1941, revised and supplemented from Intelligence Reports, 1942-44. Partially revised from aerial photography, 1942 and 1943.".