Nawaphorn Khumsiri, Ranjna Jindal, Nuttawan Yoswathana, and Woranart Jonglertjunya. 2010. “Degradation of Humic Acid in Soil Aqueous Extract Using the Fenton Reaction and a Microbiological Technique”. Agriculture and Natural Resources 44 (6). Bangkok, Thailand:1069-78. https://li01.tci-thaijo.org/index.php/anres/article/view/245082.