JAKOBČIĆ, Zvonimir. Pregled stanja telefonije u svijetu 31.12.1988. Promet - Traffic&Transportation, [S. l.], v. 3, n. 2, p. 53–70, 2012. Disponível em: https://traffic2.fpz.hr/index.php/PROMTT/article/view/1661. Acesso em: 27 aug. 2025.