Bureau of Air Commerce (part of the U.S. Department of Commerce, U.S. Federal Government) report into the investigation of the crash of an aircraft owned by the Petrol Oil Corporation on 7 May 1935
Bureau of Air Commerce
1935
National Transportation Library, U.S. Department of Transportation. <a rel="nofollow" class="external free" href="https://rosap.ntl.bts.gov/view/dot/32932">https://rosap.ntl.bts.gov/view/dot/32932</a>