Optimal sizing and cost analysis of hybrid energy storage system for EVs using metaheuristic PSO and firefly algorithms oleh Muhammad Bin Fayyaz Ahsan, Saad Mekhilef, Tey Kok Soon, Muhammad Usama, Marizan Binti Mubin, Mehdi Seyedmahmoudian, Alex Stojcevski, Hazlie Mokhlis, Prashant Shrivastava, Obaid Alshammari