Charts. Mindanao River, Delta of, and Polloc Harbor, from surveys in 1906 by Survey, in 1902-04 by officers of Navy and other sources, scale, 1: 50,000; with insets, Parang and Polloc anchorages, from survey by officers of Navy in 1902 with additions from recent Coast and Geodetic Survey work, scale 1:20,000; Mindanao River, anchorage and Cotabato Entrance, from Survey work in 1906 and from survey by officers of Navy, 1903-04, scale 1:20,000; chart 4654.