KOWALCZYK, Stanisław. PDH Systemy PDH: Sieci WAN. DEMO, Cracow, v. 12304, n. 130, 2021. DOI: 10.21641/demo.v12304i130.69. Disponível em: https://ojs.fimagis.pl/index.php/demo/article/view/69. Acesso em: 12 sep. 2025.