Nguyen, H.; Thi, P.; Dung, N.; Ngan, H.; Nhi, N.; Tri, L. Study on the Content of Some Metals in Soil by XRF Method and Evaluating Their Effect on the Total Phenolic and Flavonoid Content of Methanol Extracts from Two Medicinal Plants in An Giang Province. VNUHCM Journal of Engineering and Technology 2021, 4, 900-909.