Palestra profissional [n.º 69] A vida da telefonista / Rosa Gracinda Mateus; Administração-Geral dos Correios, Telégrafos e Telefones
Moe's Principle an econometric investigation intended as an aid in dimensioning and managing telephone plant : Theory and tables / Arne Jensen
Telephony : a detailed exposition of the telephone exchange systems of the British Post Office / J. Atkinson
100 Jahre Telephonie in Österreiche : Geschichte und Geschichten / Christine Kainz et al.; int. Karl Lausecker
Boletim dos Correios, Telégrafos e Telefones 1950 : colónia da Guiné / Ministério do Exército