1. ‘XCO2 vertical axis-wind turbine’, http://www.xco2.com November 2004
2. ‘Ropatec vertical axis wind turbine’, http://www.ropatec.com November 2004
3. ‘Windsave horizontal axis wind turbine’, http://www.windsave.comindex.htm November 2004
4. ‘Renewable devices swift turbine’, http://www.renewabledevices.com/swift.htm, November 2004