http://www.bta.bg/en/c/DF/id/1731928
https://www.strategie.gouv.fr/sites/strategie.gouv.fr/files/atoms/files/fs-livret-seminaire-soutenabilite-covid-19-mai-2020.pdf
https://docs.prosperity.com/3616/3544/3967/The_2021_Legatum_Prosperity_Index_Overview_-_Web.pdf
http://www.ilo.org/global/publications/books/WCMS_605078/lang–en/index.htm