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3. 3) Walsh, D., Weiner, S., Arifian, K., Bagai, A., Lawrence, T. and Blackwell, R.: Development Testing of the Sikorsky X2 Technology Demonstrator, 65th Annual Forum of the American Helicopter Society, Grapevine, Texas, May 27-29, 2009, pp. 1116-1126.
4. 4) Oehrle, C., Frey, F., Thiemeier, J., Keβler, M., Krämer, E., Embacher, M., Cranga, P. and Eglin, P.: Compound Helicopter X3 in High-Speed Flight: Correlation of Simulation and Flight Test, Vertical Flight Society 75th Annual Forum & Technology Display, Philadelphia, PA, May 13-16, 2019.
5. 5) AIRBUS Web, AIRBUS, https://www.airbus.com/company/history/helicopters-history/2008-2011.html（参照日 2019-8-20）