Moosa Gabeleh, Moosa, Philemon Moshokoa, and Calogero Vetro. “Cyclic (noncyclic) Phi-Condensing Operator and Its Application to a System of Differential Equations”. Nonlinear Analysis: Modelling and Control 24, no. 6 (November 7, 2019): 985–1000. Accessed July 17, 2024. https://www.journals.vu.lt/nonlinear-analysis/article/view/14847.