https://www.aljazeera.com/news/2022/12/6/chinas-xi-to-visit-saudi-arabia-from-wednesday
http://www.iata.org/publications/economic-briefings/value-of-air-cargo-2016-summary.pdf
https://www.regjeringen.no/globalassets/upload/kilde/fkd/red/2004/0009/ddd/pdfv/228920-nilf_rapport_2004_9_s.pdf