Najat Chefnaj, Khalid Hilal, and Ahmed Kajouni. “Existence of Solutions for Nonlinear Fractional Order Differential Equations With Quadratic Perturbations”. Results in Nonlinear Analysis, vol. 5, no. 3, Nov. 2022, pp. 360-71, https://nonlinear-analysis.com/index.php/pub/article/view/111.