1. 1) Cox, T. H., Nagy, C. J., Skoog, M. A. and Somers, I. A.: Civil UAV Capability Assessment (draft version), http://www.nasa.gov/centers/dryden/pdf/111761main_UAV_Capabilities_Assessment.pdf
2. 2) Infotech@Aerospace, https://www.aiaa.org/I@A2012/
3. 3) International Conference on Unmanned Aircraft Systems, http://www.uasconferences.com/
4. 4) Unmanned Aerial Vehicle Special Issue, IEEE Control Syst. Mag., 32, 5 (2012).