
https://www.bertelsmann-stiftung.de/fileadmin/files/BSt/Publikationen/GrauePublikationen/20200325_PEPP_GrundII.pdf

https://www.fraserinstitute.org/sites/default/files/economic-freedom-of-the-world-2021.pdf

https://www.populismstudies.org/wp-content/uploads/2023/03/Download-Report-on-Bulgaria.pdf