http://www.aviationlaw.eu/wp/wp-content/uploads/2013/09/Freedoms-of-the-Air-Explained.pdf
https://www.econstor.eu/bitstream/10419/266146/1/1820832732.pdf
https://rusi.org/explore-our-research/publications/commentary/ukraine-war-has-found-machinery-western-governments-wanting
https://theconversation.com/las-leyes-de-lanchester-guerras-y-ecuaciones-222469