By establishing a comparison result and using the monotone iterative technique combined with the method of upper and lower solutions, we investigate the existence of solutions for nonlinear fractional differential systems with coupled four-point boundary value problems.
Yujun Cui. Yumei Zou. "Existence Results and the Monotone Iterative Technique for Nonlinear Fractional Differential Systems with Coupled Four-Point Boundary Value Problems." Abstr. Appl. Anal. 2014 (SI58) 1 - 6, 2014. https://doi.org/10.1155/2014/242591