Aja , R. O., E. U. Agwu, S. I. Ezeh, and U. J. Stephen. “Mathematical Optimization Model Technique for Network Congestion Control in Global System for Mobile Communications”. Earthline Journal of Mathematical Sciences, Vol. 1, no. 1, Jan. 2019, pp. 51-61, doi:10.34198/ejms.1119.5161.