Doing business in the European Union 2018 [documento eletrónico] : Croatia, the Czech Republic, Portugal and Slovakia / The World Bank
Mercado das comunicações na economia nacional [documento eletrónico] : (2013-2017) / Autoridade Nacional de Comunicações
Doing business 2019 [documento eletrónico] : training for reform / The World Bank
Measuring the information society report 2018 [documento eletrónico] / International Telecommunication Union