Gurning, Kasta, Sifikal Lumbangaol, Risanti F. R Situmorang, and Saronom Silaban. 2021. “Determination of Phenolic Contents and Antioxidant Activity Test of Ethanol Extract of Sirih Merah (Piper Crocatum Ruiz & Pav.) Leaves Using the DPPH Method”. Jurnal Pendidikan Kimia 13 (2):137-42. https://doi.org/10.24114/jpkim.v13i2.26984.