Forsyth, Trudy (20 May 2009). "Small Wind Technology"(PDF). National Renewable Energy Laboratory. Archived from the original(PDF) on 17 March 2013. Retrieved 20 September 2013.
Forsyth, Trudy (20 May 2009). "Small Wind Technology"(PDF). National Renewable Energy Laboratory. Archived from the original(PDF) on 17 March 2013. Retrieved 20 September 2013.