Effendi, M. Khoirul, Bobby O. P. Soepangkat, Rachmadi Norcahyo, Suhardjono, and Sampurno. 2021. “Cutting Force and Surface Roughness Optimizations in End Milling of GFRP Composites Utilizing BPNN-Firefly Method”. International Journal of Integrated Engineering 13 (7): 297-306. https://publisher.uthm.edu.my/ojs/index.php/ijie/article/view/7924.