- City of Plovdiv: www.visitplovdiv.com
- Plovdiv Tourism: www.plovdivtourism.com
- Plovdiv 2019 – European Capital of Culture: http://plovdiv2019.eu/en
- ‘When in Bulgaria’ blogsite: https://wheninbulgaria.wordpress.com
- Flanders Investment and Trade (FIT): www.flandersinvestmentandtrade.be
- Agence Wallone à l’Exportation et aux Investissements Etrangers (AWEX): www.awex.be
- Ambassade van Bulgarije in België: http://www.bulgaria.be/embassy_vl.htm
- Ambassade van België in Bulgarije: http://www.diplomatie.be/sofianl
- CIA rapport over Bulgarie: https://www.cia.gov/library/publications/the-world-factbook/geos/bu.html
- Deloitte International Tax – Bulgaria 2018 – https://www2.deloitte.com/content/dam/Deloitte/global/Documents/Tax/dttl-tax-bulgariahighlights-2018.pdf