http://www.aviationlaw.eu/wp/wp-content/uploads/2013/09/Freedoms-of-the-Air-Explained.pdf
https://www.ceps.eu/wp-content/uploads/2013/02/1304.pdf
https://view.email.nzz.ch/?qs=a85203d2effa8cc1faa3ab144cf1943c4a23ed993d784bf2fe0a388ea4888eccfc14316e93e0269d0e2ee977e5a3905ee8c0d89191a426fe19aa026f774bc765a28c751312219b2218e7783ecd38a9f2
https://www.ipg-journal.de/regionen/europa/artikel/detail/aussenpolitik-nach-wildwest-manier-4419/