1. (2023, July 26). Clean Aviation Joint Undertaking. Available online: https://web.archive.org/web/20230726150104/https://www.clean-aviation.eu/.
2. Advisory Council for Aviation Research and Innovation in Europe, ACARE (2023, July 07). Strategic Research & Innovation Agenda (SRIA) 2017 Update, Executive Summary. Available online: http://web.archive.org/web/20230707125613/https://trimis.ec.europa.eu/sites/default/files/project/documents/acare-strategic-research-innovation-summary-2-interactive_0.pdf.
3. (2023, July 07). Clean Aviation Joint Undertaking, Strategic Research and Innovation Agenda. Available online: http://web.archive.org/web/20230707124529/https://www.clean-aviation.eu/sites/default/files/2022-01/CAJU-GB-2021-12-16-SRIA_en.pdf.
4. Bradley, M.K., and Droney, C.K. (2023, July 07). Subsonic Ultra Green Aircraft Research—Subsonic Ultra Green Aircraft Research—Phase I Final Report NASA TR CR-2011-216847, Available online: https://web.archive.org/web/20230707131352/https://ntrs.nasa.gov/api/citations/20110011321/downloads/20110011321.pdf.
5. IATA (2023, March 15). Air Passenger Market Analysis. Available online: http://web.archive.org/web/20230315083510/https://www.iata.org/en/iata-repository/publications/economic-reports/air-passenger-monthly-analysis---dec-2015.