International directory of Telecommunications : market trends, companies, statistics, and personnel / Steven Roberts; Tony Hay
New Systems and services in Telecommunications, II : proceedings of the second international conference on New Systems and Services in Telecommunications Liège, Belgium, November 16-18, 1983
Le communicateur : dossier nº 25: Telecoms et amenagement / F. Asselineau, [et all]; dir. Françoise Berthelat
Bicentenário do corpo telegráfico : 1810-2010 / António Luís Pedroso de Lima; coord. Aniceto Afonso, colab. Carlos Alves e Jorge Costa Dias, pref. Jorge Sales Golias