1. Nagy, C.J., Skoog, M.A., Somers, I.A., Cox, T.H., Warner, R.: Civil uav capability assessment. Technical report, NASA Dryden Flight Research Center (2004)
2. DeGarmo, M.T.: Issues concerning integration of unmanned aerial vehicles in civil airspace. Technical report, MITRE Center for Advanced Aviation System Development (2004)
3. Dempsey, M.: U.s army unmanned aircraft systems roadmap 2010-2035, Technical report, U.S. Army UAS Center of Excellence (2010)
4. Williamson, T., Spencer, N.A.: Development and operation of the traffic alert and collision avoidance system (tcas). In: Proceedings of the IEEE, vol. 77, pp 1735–1744 (1989)
5. Finn, A., Franklin, S.: Acoustic sense & avoid for uav’s. In: 2011 Seventh International Conference on Intelligent Sensors, Sensor Networks and Information Processing (ISSNIP), pp 586–589 (2011)