Civil Aeronautics Board report into the crash of Western Air Lines Flight 636 on 20 April 1953.
Civil Aeronautics Board, US Department of Commerce
1953-12-01
US Department of Transportation Special Collection <a rel="nofollow" class="external autonumber" href="http://specialcollection.dotlibrary.dot.gov/Document?db=DOT-AIRPLANEACCIDENTS&amp;query=(select+546)">[1]</a>