Kumar, Dileep, A. P. Singh, and V. S. Meena. 2017. “Improvement of Soil Fertility and Rice Productivity With Use of Coal Derived Humic Acid and Mineral Fertilization under Inceptisol of Varanasi, India”. International Journal of Bio-Resource and Stress Management 8 (Oct, 5):692-97. https://ojs.pphouse.org/index.php/IJBSM/article/view/1176.