CLEARN AK, SHIYAN S, PRATIWI G, . Multivariate optimization of ultrasound-assisted extraction rich polyphenol from robusta coffee fruit peel (Coffea canephora) using factorial design. Marmara Pharm. J 2019; 0(E-PUB): 2147-2163. http://dx.doi.org/10.29228/jrp.2022.00