1. The Ring Airfoil in Nonaxial Flow
2. The aerodynamics of a ring airfoil
3. FletcherH. S. “Experimental Investigation of Lift, Drag, and Pitching Moment of Five Annular Airfoils,” NACA TN 4117, Oct. 1957.
4. Aerodynamic Estimation of Annular Wings Based on Leading-Edge Suction Analogy
5. WeissingerJ. “On the Aerodynamics of Ring-Wings, I. The Pressure Distribution on a Thin, Almost Axially Symmetric Wing in Subsonic Flow,” David Taylor Model Basin Aero Rept. 899, Bethesda, MD, 1957.