Hasri, S. E. Putri, S. P. J. Negara, N. Afni, and F. Anwar, “Synthesis of NiO Nanoparticles as a Catalyst in Transesterification Reaction from Used Cooking Oil for Biodiesel Production”, sci. technol. indones., vol. 11, no. 1, pp. 280–287, Jan. 2026.