1. A vortex wake model for optimum heavily loaded ducted fans;Gray;J. Aircr.,1970
2. Contra-rotating propellers;Van Manen;Int. Shipbuild. Prog.,1956
3. M.W. Morris, Tandem propeller, US Patent 2,525,708. (1950).
4. Working Charts for the Selection of Aluminum Alloy Propellers of a Standard form to Operate With Various Aircraft Engines and Bodies;Weick,1930
5. Theoretical stability derivatives for a ducted propeller;Kriebel;J. Aircr.,1964