Zhang, Xinyu, et al. “Self-Nitrogen-Doped Biochar Derived from Soybean Cake for Rhodamine B Removal Prepared via Simple Carbonization”. BioResources, vol. 18, no. 4, Sept. 2023, pp. 7460-73, https://ojs.bioresources.com/index.php/BRJ/article/view/22806.