Tangsombatvichit, Pitchya, Thidarat Tiammongkol, and Nareerat Konganan. “Immobilized Free Nitrogen-Fixing Bacteria Azotobacter in Natural Materials and Its Effect on Growth of Brassica Chinensis in Soil”. RMUTP Research Journal Sciences and Technology 15, no. 2 (December 31, 2021): 158–168. Accessed May 5, 2024. https://ph02.tci-thaijo.org/index.php/RMUTP/article/view/242243.