Almalahi MA, Panchal SK. Existence and $\delta $-Approximate solution of implicit fractional pantograph equations in the frame of Hilfer-Katugampola operator. J Frac Calc & Nonlinear Sys [Internet]. 2021 Jun. 29 [cited 2026 Apr. 16];2(1):1-17. Available from: https://www.sabapub.com/index.php/jfcns/article/view/59