ERGP report on the future needs of the USO [documento eletrónico] / European Regulators Group for Postal Services
O sector das comunicações 2022 [documento eletrónico] / Autoridade Nacional de Comunicações
International communications within the EU [documento eletrónico] / European Commission
Measuring digital development [documento eletrónico] : facts and figures; : focus on least developed countries / International Telecommunication Union