Helwani, Z., Amraini, S. Z., Asmura, J., Siregar, T. N., Triwahyuni, V. E. and Abd , A. A. (2023) “Palm Frond Waste as a Carbon Source in the Synthesis of CaO/Biochar Catalysts for the Biodiesel Production Process”, Heca Journal of Applied Sciences, 1(1), pp. 8–13. doi: 10.60084/hjas.v1i1.9.