http://www.congreso.es/public_oficiales/L13/CONG/BOCG/B/BOCG-13-B-29-1.PDF#page=1
http://eur-lex.europa.eu/legal-content/EN/TXT/PDF/?uri=CELEX:52017SC0201&from=EN
http://www.bta.bg/en/c/DF/id/1731928
https://nationalaffairs.com/publications/detail/markets-for-the-people