S. Phowichit, P. Ratanachamnong, U. Matsathit, and W. Ussawawongaraya, “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, vol. 18, no. 1, pp. 25–39, Jun. 2019.