M.I. UMAR; M.U. ADEHI; M.A. AUWAL. A Systematic Review of Multi-Server Queueing System: A Case of Lengthy Wait Times in Hospital Medical Outpatient Department (OPD). African Journal of Advances in Science and Technology Research, [S. l.], v. 12, n. 1, p. 01–17, 2023. Disponível em: https://publications.afropolitanjournals.com/index.php/ajastr/article/view/601. Acesso em: 2 nov. 2026.