F. Alfiany, N. E. K. Putri, and F. Prasetya, “Optimasi Basis Formulasi Sediaan Handsanitizer Gel Ekstrak Daun Sirih Hitam (Piper betle var nigra) Sebagai Antibakteri: Optimization of the Hand Sanitizer Gel Preparation Base for Black Betel Leaf Extract (Piper betle var nigra) as an antibacterial”, Proc. Mul. Pharm. Conf., vol. 14, no. 1, pp. 186–189, Dec. 2021.