
https://www.imf.org/-/media/Files/Countries/ResRep/ECC/corporate-liquidity-and-solvency-in-europe-feb-12-2021-v3.ashx

https://www.mckinsey.com/industries/public-and-social-sector/our-insights/covid-19-and-european-small-and-medium-size-enterprises-how-they-are-weathering-the-storm#

http://www.iata.org/publications/economic-briefings/value-of-air-cargo-2016-summary.pdf