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

https://static1.squarespace.com/static/5e449c8c3ef68d752f3e70dc/t/65cd2ea60b24286e268de92d/1707945639018/Hanley+-+Writing+Law+%28Indicators+of+a+Favorable+Statute%29+-+FINAL.pdf

https://europeanchamber.oss-cn-beijing.aliyuncs.com/upload/documents/documents/The_Shape_of_Things_to_Come_EN_final[966].pdf