
https://papers.ssrn.com/sol3/Delivery.cfm/SSRN_ID4092831_code1752653.pdf?abstractid=4092831&mirid=1

https://corporateeurope.org/sites/default/files/driving_into_disaster_report_final_0.pdf

http://www.aviationlaw.eu/wp/wp-content/uploads/2013/09/Freedoms-of-the-Air-Explained.pdf