Langley and Manly: Langley Memoir on Mechanical Flight, Part 1 1887 to 1896 and Part 2 1897 to 1903, published by Smithsonian Institution, 1948 edition; Turner, Charles C: The Marvels of Aviation, 1918; Cobham, Alan J: My Flight to the Cape and Back, 1926; five others of similar interest and six pamphlets (15)