Phowichit, S.; Ratanachamnong, P.; Matsathit, U.; Ussawawongaraya, W. Anti-Oxidant Activity, Phenolic and Flavonoid Constituents of Crude Extracts from Piper Ribesioides and Zanthoxylum Limonella Traditional Herbal Medicine in Northern Thailand. J Appl Res Sci Tech 2019, 18, 25-39.