http://www.aviationlaw.eu/wp/wp-content/uploads/2013/09/Freedoms-of-the-Air-Explained.pdf
https://wiiw.ac.at/different-choices-divergent-paths-poland-and-ukraine-dlp-6419.pdf
https://www.aljazeera.com/news/2022/12/6/chinas-xi-to-visit-saudi-arabia-from-wednesday
https://papers.ssrn.com/sol3/papers.cfm?abstract_id=3305056