"Prepared by the Army Map Service (SX), Corps of Engineers, U.S. Army, Washington, D.C. Compiled in 1967 by photogrammetric methods. Aerial photography dated December 1961. Field classification 1964 by the Instituto Geográfico Militar, Lima, Perú and the Inter-American Geodetic Survey. Horizontal and vertical control by the Instituto Geográfico Militar, Lima, Perú and the Inter-American Geodetic Survey".