https://www.imf.org/en/Publications/fandd/issues/2022/09/Bullet-train-Adrian-Mancini-Griffoli
https://www.airhelp.com/en-int/airhelp-score/
https://www.enterpriseresearch.ac.uk/wp-content/uploads/2019/06/02114-State-of-Small-Business-Britain-Report_June-2019-Final.pdf
https://www.bwb.gv.at/fileadmin/user_upload/Abschlussbericht_BU_Kraftstoffe_2022_final_barrierefrei.pdf