Giyanto, et al. “Utilization of Coconut Shells As a Source of Graphene Nanosheets Fe N-GNS for Environmentally Friendly Primary Battery Electrodes”. Piston: Journal of Technical Engineering, vol. 9, no. 2, Jan. 2026, pp. 85-89, https://openjournal.unpam.ac.id/index.php/Piston/article/view/57488.