https://ukandeu.ac.uk/is-economic-output-an-accurate-measure-of-the-covid-19-impact/
https://www.sra.org.uk/pdfcentre/?type=Id&data=1772866600
http://www.iata.org/publications/economic-briefings/value-of-air-cargo-2016-summary.pdf
https://www.economiesuisse.ch/de/artikel/neue-oecd-leitsaetze-fuer-multinationale-unternehmen