Telephones in Norway 1880-2000 : 1880-2000 / Terje Ellefsen, Anne Solberg and Cato Normann; trad. Apropos and David Brand
Hallo?! : Norges telefonhistorie / Tor Edwin Dahl, Terje Ellefsen e Anne Solberg; int. Christian Westring; fot. Olav Lorck Eidem