marhaini ., E. Sri Yusmartini, D. Fernianti, and L. Okka Widhanny, “Transesterification of biodiesel from kapok seed oil (ceiba pentandra) using a natural heterogeneous katalyst (rice husk activation)”, IJAC, vol. 11, no. 2, pp. 15–19, Oct. 2023, doi: 10.14419/36w3ym34.