1. Rohacs, J. (2002, January 8–13). PATS. Proceedings of the 23rd International Congress of Aeronautical Sciences, Toronto, ON, Canada.
2. Parker, R.A. (2017). NASA Strategic Framework for On-Demand Air Mobility NASA Headquarters, National Institute of Aerospace.
3. (2020, November 10). NASA Embraces Urban Air Mobility, Calls for Market Study, Available online: https://www.nasa.gov/aero/nasa-embraces-urban-air-mobility.
4. (2021, November 13). Uber Elevate | The Future of Urban Air Transport. Available online: https://www.uber.com/info/elevate/.
5. Holden, J., and Goel, N. (2016). Fast-Forwarding to a Future of On-Demand Urban Air Transportation, UBER.