https://www.mckinsey.com/mgi/our-research/the-complication-of-concentration-in-global-trade
https://www.wto.org/english/res_e/booksp_e/gvc_dev_report_2019_e.pdf
http://www.iata.org/publications/economic-briefings/value-of-air-cargo-2016-summary.pdf
https://borderlex.net/2021/04/13/comment-quo-vadis-energy-charter-treaty/