Michael Swords, comp., “Cases at the Beginning of the Modern UFO Era: Kenneth Arnold, June 24, 1947,” Historical Document Series, No. 1 (J. Allen Hynek Center for UFO Studies, Oct. 1992); and Kenneth Arnold and Raymond Palmer, The Coming of the Saucers (Amherst, WS: Legend Press, n.d.), 9-15. Also, “The 1947 Kenneth Arnold UFO Sighting” from: http://www.ufoevidence.org/cases/case511.htm. Arnold provided a drawing for the Army Air Force, dated 12 July 1947. Available online from: http://upload.wikimedia.org/wikipedia/commons/d/d1/Arnold_AAF_drawing.jpg.