https://www.ifo.de/DocDL/EEAG-2019-executive-summary.pdf
https://cepr.org/sites/default/files/policy_insights/PolicyInsight92.pdf
http://library.fes.de/pdf-files/bueros/rom/16042.pdf
https://wwfeu.awsassets.panda.org/downloads/ets_revenues_report_2022___web___final.pdf