1. D. Biermann, W.H. Gray, Wind-Tunnel Tests of Eight–blade Single and Dual-Rotating Pusher Propellers in the Tractor Position. NACA ARR, 1941.
2. D. Biermann, W.H. Gray, J.D. Maynard, Wind-Tunnel Tests of Single-and Dual-Rotating Tractor Propellers of Large Blade Width, NACA WARTIME REPORTS, 1942.
3. D. Biermann, W.H. Gray, Wind-Tunnel Tests of Single-and Dual-Rotating Pusher Propellers Having from Three to Eight Blades, NACA ARR (WR L-359), 1942.