Boulton Paul P.64 Mailplane 3-view drawing from NACA-AC-177
NACA Aircraft Circular
1933-04-01
<a rel="nofollow" class="external free" href="https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19930090486.pdf">https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19930090486.pdf</a>