The First Man-Carrying Aeroplane Capable of Sustained Free Flight :
Zahm, Albert Francis
The First Man-Carrying Aeroplane Capable of Sustained Free Flight : Langley's Success as a Pioneer in Aviation : From the Smithsonian Report for 1914, pages 217-222, Publication 2329, 1915 [electronic resource] / Albert Francis Zahm - Project Gutenberg, 2013 - Project Gutenberg 44466 .
Public domain in the USA.
Electronic text
The First Man-Carrying Aeroplane Capable of Sustained Free Flight : Langley's Success as a Pioneer in Aviation : From the Smithsonian Report for 1914, pages 217-222, Publication 2329, 1915 [electronic resource] / Albert Francis Zahm - Project Gutenberg, 2013 - Project Gutenberg 44466 .
Public domain in the USA.
Electronic text