Nyoman Ehrich Lister, I., C. N. Ginting, E. Girsang, A. Armansyah, H. H. Marpaung, A. P. F. Sinaga, R. Anisa Siwianti Handayani, and R. Rizal. “Antioxidant Properties of Red Betel (<i>Piper crocatum</I>) Leaf Extract and Its Compounds”. Journal of Natural Remedies, vol. 19, no. 4, Jan. 2020, pp. 198-05, doi:10.18311/jnr/2019/23633.