“Existence, Uniqueness, Ulam Stability and Continuous Dependence of Mild Nonnegative Solutions for an Iterative Fractional Relaxation Differential Equation”. Nonlinear Studies, vol. 33, no. 1, Feb. 2026, pp. 21`9-234, https://www.nonlinearstudies.com/index.php/nonlinear/article/view/4152.