Schiffer. 1973. OCLC 38286714. U.S. CoastandGeodeticSurvey. Report of the Superintendent of the U.S. CoastandGeodeticSurvey Showing the Progress of the
在德奎島西方約3公里處,有一座頂點於海平面以下24公尺的山 。 島嶼距離沃荷斯島約0.5公里,相距臺灣蘭嶼大約200公里左右。 U.S. CoastandGeodeticSurvey, "United States Coast Pilot, Philippine Islands, Part I", p.40. Washington
Captain (retired). A Geodetic Measurement of Unusually High Accuracy (PDF). U.S. CoastandGeodeticSurvey Journal (CoastandGeodeticSurvey). April 1949: 68–74
Retrieved March 12, 2016 Department of Commerce, U.S. CoastandGeodeticSurvey, "United States Coast Pilot, Part 1", p. 203. Washington Government Printing