Runji, F.M., Agure, J.O. & Nyamwala, F.O., 2017. On the maximal numerical range of elementary operators.
Nyamwala, F.O., 2017. Essential and continuous spectrum of symmetric difference equations. Mathematische Nachrichten, 290, p.2977–2991.
Nyamwala, F.O., 2015. Absolutely continuous spectrum of fourth order difference equations. Mathematische Nachrichten, 288, p.1009–1027.
Denis, N.K., John, O.A. & Fredrick, O.N., 2014. On the Norm of Elementary Operator. Advances in Pure Mathematics, 4, p.309–316.