- United States Department of Energy Office of Energy Efficiency and Renewable Energy. 20% Wind Energy by 2030: Increasing Wind Energy's Contribution to US Electrical Supply (pdf): 15. 2008-05-20 [2008-12-11].
- AEP- American Electric Power Inc. Interstate Transmission Vision for Wind Integration (PDF): 1. 2007-06-25 [2008-12-11]. （原始内容 (pdf)存档于2016-03-09）.
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