Analysis and Development of Customer Billing Telephony System. Baghdad Science Journal, Iraq, Baghdad, v. 16, n. 2(SI), p. 0428, 2019. DOI: 10.21123/bsj.2019.16.2(SI).0428. Disponível em: https://bsj.uobaghdad.edu.iq/index.php/BSJ/article/view/3558.. Acesso em: 6 may. 2024.