<ul><li><a href=https://www.boe.es/buscar/act.php?id=BOE-A-2010-20139# target=_blank>Law on universal postal services, the rights of users and the postal market(Ley 43/2010 del servicio postal universal, de los derechos de los usuarios y del mercado postal, adopted on 30 December 2010, last amended on 2 November 2013, Articles 21-22 and 37-38)</a></li><li><a href=https://www.cnmc.es/sites/default/files/3857521_2.pdf target=_blank>Spanish Competition Authority Report(2020 Report on the Postal and Courier Sectors. See section 5.3.3.4. )</a></li></ul>