Liu, Lixiu, Aijiang He, and Xiangbiao Li. “Synthesis of Allantoin Catalyzed by SO42- La2O3-SiO2-ZrO2”. Asian Journal of Chemistry 24, no. 5 (January 3, 2012): 2298–2300. Accessed November 24, 2024. https://asianpubs.org/index.php/ajchem/article/view/9004.