F. O. Ehiagwina, A. O. Fakolujo, S. A. Afolabi, Y. A. Abdulraman, and L. O. Afolabi, “An Overview of Multi-Operator Global Systems for Mobile Communications Base Stations in the Context of Nigerian Telecommunication Sector”, EJENG, vol. 1, no. 1, pp. 50–55, Jul. 2018.