M. A. Yahya and I. H. Nurrosyidah, “Antioxidant activity ethanol extract of gotu kola (Centella asiatica (L.) Urban) with DPPH method (2,2-Diphenyl-1-Pikrilhidrazil)”, J.halal prod. Res., vol. 3, no. 2, pp. 106–112, Nov. 2020.