Nuon, Dina. “Effects of leonardite and nutrient management on growth and yield of cowpea (Vigna unguiculata L. Walp.)”. Journal of Science and Agricultural Technology 3, no. 1 (June 8, 2022): 25–29. accessed April 22, 2026. https://ph02.tci-thaijo.org/index.php/JSAT/article/view/245816.