Musbah, E. M. M., K. H. Bilal, and N. Mustafa. “Comparison of QoS Performance over WLAN, VoIP4 and VoIP6”. International Research Journal of Management, IT and Social Sciences, vol. 2, no. 11, Nov. 2015, pp. 29-37, https://sloap.org/journals/index.php/irjmis/article/view/325.