1. ICAO. Cir 328 AN/190 unmanned aircraft systems (UAS). Technical report, ICAO (2011)
2. EASA. Concept of operation for Drones: a risk based approach to regulation of unmanned aircraft. European Aviation Safety Agency (2015)
3. EASA. Introduction of a regulatory framework for the operation of unmanned aircraft, technical opinion. European Aviation Safety Agency (2015)
4. EASA. Introduction of a regulatory framework for the operation of Drones, notice of proposed amendment, NPA 2017-5. European Aviation Safety Agency (2017)
5. H.-M. Huang, E. Messina, J. Albus, Autonomy levels for unmanned systems (ALFUS) framework - volume II: framework models version 1.0. Technical report, NIST special publication 1011-II-1.0. National Institute of Standards and Technology (NIST) (2007)