Jiang, Ruiting, and Chengbo Zhai. “Positive Solutions for a System of Fourth-Order Differential Equations With Integral Boundary Conditions and Two Parameters”. Nonlinear Analysis: Modelling and Control 23, no. 3 (June 15, 2018): 401–422. Accessed October 30, 2026. https://journals.vu.lt/nonlinear-analysis/article/view/13193.