VALDAR, Andy. The Potential Cyber and Network Security Issues of PSTN Closure. Journal of Telecommunications and Information Technology, [S. l.], n. Special Issue, p. 18–24, 2025. DOI: 10.26636/jtit.2025.FITCE2024.2021. Disponível em: https://www.jtit.pl/jtit/article/view/2021. Acesso em: 11 may. 2026.