1. Betz A. Wind-Energie und ihre Ausnutzung durch Windmuehlen. Oekobuch reprint, Staufen.
2. New high profitable wind turbines;Frankovic;Renewab Energy,2001
3. Windturbines;Hau,2000
4. Oman et al. Variable stator, diffuser augmented wind turbine electrical generation system. US patent 4,075,500.
5. Based on the patent [4], the company Vortec of New Zealand has made several prototypes.