De Havilland DH.84 Dragon detail drawing from NACA-AC-174
NACA Aircraft Circular
1933-01-01
<a rel="nofollow" class="external free" href="https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19930090482.pdf">https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19930090482.pdf</a>